WO2018130569A1 - Catalyseurs pour traiter des gaz d'échappement - Google Patents

Catalyseurs pour traiter des gaz d'échappement Download PDF

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Publication number
WO2018130569A1
WO2018130569A1 PCT/EP2018/050559 EP2018050559W WO2018130569A1 WO 2018130569 A1 WO2018130569 A1 WO 2018130569A1 EP 2018050559 W EP2018050559 W EP 2018050559W WO 2018130569 A1 WO2018130569 A1 WO 2018130569A1
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Prior art keywords
washcoat
particles
micron
alumina
substrate
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PCT/EP2018/050559
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English (en)
Inventor
Qinghua Yin
Xiwang Qi
Bryant KEARL
Maximillian A. Biberger
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Umicore Ag & Co. Kg
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Publication of WO2018130569A1 publication Critical patent/WO2018130569A1/fr

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/02—Impregnation, coating or precipitation
    • B01J37/03—Precipitation; Co-precipitation
    • B01J37/038—Precipitation; Co-precipitation to form slurries or suspensions, e.g. a washcoat
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/92—Chemical or biological purification of waste gases of engine exhaust gases
    • B01D53/94—Chemical or biological purification of waste gases of engine exhaust gases by catalytic processes
    • B01D53/944—Simultaneously removing carbon monoxide, hydrocarbons or carbon making use of oxidation catalysts
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J21/00—Catalysts comprising the elements, oxides, or hydroxides of magnesium, boron, aluminium, carbon, silicon, titanium, zirconium, or hafnium
    • B01J21/02—Boron or aluminium; Oxides or hydroxides thereof
    • B01J21/04—Alumina
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/38—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals
    • B01J23/54—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals combined with metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36
    • B01J23/56—Platinum group metals
    • B01J23/63—Platinum group metals with rare earths or actinides
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J35/00—Catalysts, in general, characterised by their form or physical properties
    • B01J35/19—Catalysts containing parts with different compositions
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J35/00—Catalysts, in general, characterised by their form or physical properties
    • B01J35/50—Catalysts, in general, characterised by their form or physical properties characterised by their shape or configuration
    • B01J35/56—Foraminous structures having flow-through passages or channels, e.g. grids or three-dimensional monoliths
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J35/00—Catalysts, in general, characterised by their form or physical properties
    • B01J35/60—Catalysts, in general, characterised by their form or physical properties characterised by their surface properties or porosity
    • B01J35/61—Surface area
    • B01J35/615—100-500 m2/g
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/02—Impregnation, coating or precipitation
    • B01J37/024—Multiple impregnation or coating
    • B01J37/0244—Coatings comprising several layers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/08—Heat treatment
    • B01J37/082—Decomposition and pyrolysis
    • B01J37/088—Decomposition of a metal salt
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2255/00—Catalysts
    • B01D2255/10—Noble metals or compounds thereof
    • B01D2255/102—Platinum group metals
    • B01D2255/1021—Platinum
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2255/00—Catalysts
    • B01D2255/10—Noble metals or compounds thereof
    • B01D2255/102—Platinum group metals
    • B01D2255/1023—Palladium
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2255/00—Catalysts
    • B01D2255/20—Metals or compounds thereof
    • B01D2255/206—Rare earth metals
    • B01D2255/2065—Cerium
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2255/00—Catalysts
    • B01D2255/20—Metals or compounds thereof
    • B01D2255/209—Other metals
    • B01D2255/2092—Aluminium
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2255/00—Catalysts
    • B01D2255/90—Physical characteristics of catalysts
    • B01D2255/902—Multilayered catalyst
    • B01D2255/9022—Two layers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2255/00—Catalysts
    • B01D2255/90—Physical characteristics of catalysts
    • B01D2255/92—Dimensions
    • B01D2255/9202—Linear dimensions
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2255/00—Catalysts
    • B01D2255/90—Physical characteristics of catalysts
    • B01D2255/92—Dimensions
    • B01D2255/9207—Specific surface
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2523/00—Constitutive chemical elements of heterogeneous catalysts

Definitions

  • the present disclosure relates to the field of catalysts for treating exhaust gas, including exhaust gas resulting from the combustion of natural gas, combustible hydrocarbon liquids, oil, kerosene, coal, or wood and other organic fuels.
  • Catalysts for treating exhaust gas generally use platinum group metals to oxidize or reduce gases in the exhaust gas. For example, carbon monoxide can be oxidized to less harmful carbon dioxide.
  • platinum group metals are expensive, and significant amounts of platinum group metal can make the cost of a catalyst for treating exhaust gas to be unaffordable for many consumers.
  • a catalyst comprising a substrate coated with a first washcoat layer and a second washcoat layer; the first washcoat layer comprising porous micron- sized particles comprising ceria impregnated with palladium, and alumina derived from boehmite particles; and the second washcoat layer comprising porous micron-sized particles comprising alumina impregnated with platinum, and alumina derived from boehmite particles.
  • the micron-sized particles comprising ceria in the first washcoat layer are impregnated with palladium by wet-chemistry methods.
  • the micron-sized particles comprising alumina in the second washcoat layer are impregnated with platinum by wet-chemistry methods.
  • the boehmite particles used to derive the alumina in the first washcoat layer have an average dispersed particle size of about 60 nm or less. In some embodiments, the boehmite particles used to derive the alumina in the first washcoat layer have a BET surface area of about 120 m 2 /e or more. In some embodiments, the boehmite particles used to derive the alumina in the second washcoat layer have an average dispersed particle size of about 150 nm or more. In some embodiments, the boehmite particles used to derive the alumina in the second washcoat layer have a BET surface area of about 250 m 2 /g or less.
  • the micron-sized particles comprising alumina in the second washcoat layer are stabilized with lanthana.
  • the first washcoat layer further comprises porous micron-sized particles comprising alumina.
  • the porous micron-sized particles comprising alumina in the first washcoat layer are impregnated with palladium.
  • the porous micron-sized particles comprising alumina in the first washcoat layer are impregnated with palladium by wet-chemistry methods.
  • the porous micron-sized particles comprising alumina in the first washcoat layer are substantially free of palladium.
  • the micron-sized particles comprising alumina are stabilized with lanthana.
  • the micron-sized particles comprising alumina in the first washcoat layer make up about 2 wt% to about 10 wt% of the solids in the first washcoat layer.
  • the alumina derived from boehmite in the first washcoat layer makes up about 2 wt% to about 15 wt% of the solids in the first washcoat layer. In some embodiments, the alumina derived from boehmite in the second washcoat layer makes up about 1 wt% to about 8 wt% of the solids in the second washcoat layer.
  • the first washcoat layer has a thickness of about 100 g/1 to about 300 g/1. In some embodiments, the second washcoat layer has a thickness of about 40 g/1 to about 150 g/1.
  • the first washcoat layer has a palladium loading of about 0.1 g/1 to about 0.5 g/1.
  • the second washcoat layer has a platinum loading of about 0.2 g/1 to about 0.7 g/1.
  • the catalyst has a platinum group metal loading of about 0.3 g/1 to about 1.2 g/1.
  • the micron-sized particles comprising ceria in the first washcoat layer make up about 60 wt% to about 95 wt% of the solids in the first washcoat layer.
  • the micron-sized particles comprising alumina in the second washcoat layer make up about 85 wt% to about 99 wt% of the solids in the second washcoat layer.
  • the substrate comprises cordierite. In some embodiments, the substrate has a honeycomb structure. In some embodiments, the substrate is about 0.5 cm to about 6 cm thick. In some embodiments, the substrate has a transverse profile of about 100 cm 2 to about 600 cm 2 .
  • an exhaust treatment system comprising a conduit for exhaust gas and any one of the catalysts described above.
  • the catalyst is fluidly connected to an exhaust gas source.
  • the exhaust gas source burns natural gas, a combustible hydrocarbon liquid, oil, kerosene, coal, or wood.
  • the exhaust gas source is a stove, a furnace, a fireplace, or a generator.
  • a method of treating an exhaust gas comprising contacting the exhaust gas with any one of the catalysts described above.
  • a method of making a catalyst comprising (1) coating a substrate with a first washcoat composition comprising porous micron-sized particles comprising ceria, a palladium salt, and boehmite particles, or comprising porous micron-sized particles comprising ceria impregnated with palladium, and boehmite particles; and (2) coating the substrate with a second washcoat composition comprising porous micron-sized particles comprising alumina, a platinum salt, and boehmite particles, or comprising porous micron-sized particles comprising alumina impregnated with platinum, and boehmite particles.
  • the first washcoat composition comprises porous micron-sized particles comprising ceria, a palladium salt, and boehmite particles. In some embodiments, the first washcoat composition comprises porous micron-sized particles comprising ceria impregnated with palladium, and boehmite particles. In some embodiments, the second washcoat composition comprises porous micron-sized particles comprising ceria impregnated with palladium, and boehmite particles. In some embodiments, the second washcoat composition comprises porous micron-sized particles comprising alumina impregnated with platinum, and boehmite particles.
  • the method further comprises drying the first washcoat composition after it has been coated onto the substrate. In some embodiments, the method further comprises calcining the substrate after the first washcoat composition has been coated onto the substrate. In some embodiments, the method comprises drying the second washcoat composition after it has been coated onto the substrate. In some embodiments, the method comprises calcining the substrate after the second washcoat composition has been coated onto the substrate.
  • the substrate is coated with the first washcoat composition prior to being coated with the second washcoat composition.
  • the boehmite particles in the first washcoat composition have an average dispersed particle size of about 60 nm or less. In some embodiments, the boehmite particles in the first washcoat composition have a BET surface area of about 120 m 2 /s or more. In some embodiments, the boehmite particles in the second washcoat layer have an average dispersed particle size of about 150 nm or more. In some embodiments, the boehmite particles in the second washcoat layer have a BET surface area of about 250 m 2 /g or less.
  • the micron-sized particles comprising alumina in the second washcoat composition are stabilized with lanthana.
  • the first washcoat composition further comprises porous micron-sized particles comprising alumina.
  • the micron-sized particles comprising alumina in the first washcoat composition are stabilized with lanthana.
  • the micron-sized particles comprising alumina in the first washcoat composition make up about 2 wt% to about 10 wt% of the solids in the first washcoat composition.
  • the boehmite particles in the first washcoat composition make up about 2 wt% to about 15 wt% of the solids in the first washcoat composition. In some embodiments, the boehmite particles in the second washcoat composition make up about 1 wt% to about 8 wt% of the solids in the second washcoat composition.
  • the first washcoat composition is coated onto the substrate at a thickness of about 100 g/1 to about 300 g/1 of solids.
  • the second washcoat composition is coated onto the substrate at a thickness of about 40 g/1 to about 150 g/1 of solids.
  • the first washcoat composition is coated onto the substrate to obtain a palladium loading of about 0.1 g/1 to about 0.5 g/1.
  • the second washcoat composition is coated onto the substrate to obtain a platinum loading of about 0.2 g/1 to about 0.7 g/1.
  • the micron-sized particles comprising ceria make up about 80 wt% to about 95 wt% of the solids in the first washcoat composition. In some embodiments, the micron-sized particles comprising alumina make up about 85 wt% to about 99 wt% of the solids in the second washcoat composition.
  • the substrate comprises cordierite.
  • the substrate has a honeycomb structure.
  • the substrate is about 1 cm to about 4 cm thick.
  • the substrate has a transverse profile of about 100 to about 600 cm 2 .
  • the present invention pertains to a catalyst comprising:
  • the first washcoat layer comprising porous micron-sized particles comprising ceria impregnated with palladium, and alumina derived from boehmite particles; and the second washcoat layer comprising porous micron-sized particles comprising alumina impregnated with platinum, and alumina derived from boehmite particles.
  • the micron-sized particles comprising ceria in the first washcoat layer are impregnated with palladium by wet-chemistry methods.
  • the micron-sized particles comprising alumina in the second washcoat layer are impregnated with platinum by wet-chemistry methods.
  • the boehmite particles used to derive the alumina in the first washcoat layer have an average dispersed particle size of about 60 nm or less. More preferably the boehmite particles used to derive the alumina in the first washcoat layer have a BET surface area of about 120 m2/g or more.
  • the boehmite particles used to derive the alumina in the second washcoat layer have an average dispersed particle size of about 150 nm or more. More preferably, the boehmite particles used to derive the alumina in the second washcoat layer have a BET surface area of about 250 m2/g or less.
  • the micron-sized particles comprising alumina in the second washcoat layer are stabilized with lanthana.
  • the first washcoat layer further comprises porous micron-sized particles comprising alumina. More preferably, the porous micron-sized particles comprising alumina in the first washcoat layer are impregnated with palladium. Even more preferably, the porous micron-sized particles comprising alumina in the first washcoat layer are impregnated with palladium by wet-chemistry methods. [0037] In the above mentioned catalyst, also preferably, the porous micron-sized comprising alumina in the first washcoat layer are substantially free of palladium.
  • the micron-sized particles of the first washcoat layer comprising alumina are stabilized with lanthana.
  • the micron-sized particles comprising alumina in the first washcoat layer make up about 2 wt% to about 10 wt% of the solids in the first washcoat layer.
  • the alumina derived from boehmite in the first washcoat layer makes up about 2 wt% to about 15 wt% of the solids in the first washcoat layer.
  • the alumina derived from boehmite in the second washcoat layer makes up about 1 wt% to about 8 wt% of the solids in the second washcoat layer.
  • the first washcoat layer has a thickness of about 100 g/1 to about 300 g/1.
  • the second washcoat layer has a thickness of about 40 g/1 to about 150 g/1.
  • the first washcoat layer has a palladium loading of about 0.1 g/1 to about 0.5 g/1.
  • the second washcoat layer has a platinum loading of about 0.2 g/1 to about 0.7 g/1.
  • the catalyst has a platinum group metal loading of about 0.3 g/1 to about 1.2 g/1.
  • the micron-sized particles comprising ceria in the first washcoat layer make up about 60 wt% to about 95 wt% of the solids in the first washcoat layer.
  • the micron-sized particles comprising alumina in the second washcoat layer make up about 85 wt% to about 99 wt% of the solids in the second washcoat layer.
  • the substrate comprises cordierite. Further preferably, the substrate has a honeycomb structure. Also further preferably, the substrate is about 0.5 cm to about 6 cm thick. Also preferably, the substrate has a transverse profile of about 100 cm 2 to about 600 cm 2 .
  • the present invention pertains to an exhaust treatment system comprising a conduit for exhaust gas and the catalyst as mentioned above.
  • the catalyst is fluidly connected to an exhaust gas source.
  • the exhaust gas source burns natural gas, a combustible hydrocarbon liquid, oil, kerosene, coal, or wood.
  • the exhaust gas source is a stove, a furnace, a fireplace, or a generator.
  • the present invention also pertains to a method of treating an exhaust gas comprising contacting the exhaust gas with the catalyst as mentioned above.
  • the present invention pertains to a method of making a catalyst comprising: i. coating a substrate with a first washcoat composition comprising:
  • porous micron-sized particles comprising ceria, a palladium salt, and boehmite particles, or porous micron-sized particles comprising ceria impregnated with palladium, and boehmite particles;
  • porous micron-sized particles comprising alumina, a platinum salt, and boehmite particles, or porous micron-sized particles comprising alumina impregnated with platinum, and boehmite particles.
  • the first washcoat composition comprises porous micron-sized particles comprising ceria, a palladium salt, and boehmite particles. More preferably, the first washcoat composition comprises porous micron-sized particles comprising ceria impregnated with palladium, and boehmite particles.
  • the second washcoat composition comprises porous micron- sized particles comprising ceria impregnated with palladium, and boehmite particles.
  • the second washcoat composition comprises porous micron-sized particles comprising alumina impregnated with platinum, and boehmite particles.
  • This method preferably, further comprises drying the first washcoat composition after it has been coated onto the substrate. More preferably, the method further comprises calcining the substrate after the first washcoat composition has been coated onto the substrate.
  • This method preferably, further comprises drying the second washcoat composition after it has been coated onto the substrate. More preferably, the method further comprises calcining the substrate after the second washcoat composition has been coated onto the substrate.
  • the substrate is coated with the first washcoat composition prior to being coated with the second washcoat composition.
  • the boehmite particles in the first washcoat composition have an average dispersed particle size of about 60 nm or less. Also preferably, the boehmite particles in the first washcoat composition have a BET surface area of about 120 m2/g or more.
  • the boehmite particles in the second washcoat layer have an average dispersed particle size of about 150 nm or more. Also preferably, the boehmite particles in the second washcoat layer have a BET surface area of about 250 m2/g or less.
  • the micron-sized particles comprising alumina in the second washcoat composition are stabilized with lanthana.
  • the first washcoat composition further comprises porous micron-sized particles comprising alumina. More preferably, the micron-sized particles comprising alumina in the first washcoat composition are stabilized with lanthana.
  • the micron-sized particles comprising alumina in the first washcoat composition make up about 2 wt% to about 10 wt% of the solids in the first washcoat composition. More preferably, the boehmite particles in the first washcoat composition make up about 2 wt% to about 15 wt% of the solids in the first washcoat composition.
  • the boehmite particles in the second washcoat composition make up about 1 wt% to about 8 wt% of the solids in the second washcoat composition.
  • the first washcoat composition is coated onto the substrate at a thickness of about 100 g/1 to about 300 g/1 of solids.
  • the second washcoat composition is coated onto the substrate at a thickness of about 40 g/1 to about 150 g/1 of solids.
  • the first washcoat composition is coated onto the substrate to obtain a palladium loading of about 0.1 g/1 to about 0.5 g/1.
  • the second washcoat composition is coated onto the substrate to obtain a platinum loading of about 0.2 g/1 to about 0.7 g/1.
  • the micron-sized particles comprising ceria make up about 80 wt% to about 95 wt% of the solids in the first washcoat composition.
  • the micron-sized particles comprising alumina make up about 85 wt% to about 99 wt% of the solids in the second washcoat composition.
  • the substrate comprises cordierite. Also preferably, the substrate has a honeycomb structure. Also preferably, the substrate is about 1 cm to about 4 cm thick. Still further preferably, the substrate has a transverse profile of about 100 cm 2 to about 600 cm 2.
  • the present invention pertains to a catalyst made according to the method mentioned above.
  • FIG. 1 A illustrates one method of forming the catalyst in accordance with some embodiments of the present invention.
  • FIG. IB illustrates one embodiment of a catalyst including a substrate coated with the first washcoat layer and the second washcoat layer.
  • FIG. 2 shows the amount of carbon monoxide exiting a reference catalyst (Catalyst A) and two embodiments of the catalyst described herein (Catalyst B and Catalyst C) plotted against the temperature of the exhaust gas.
  • a substrate coated with a first washcoat layer and a second washcoat layer comprising porous micron-sized particles comprising ceria impregnated with palladium, and alumina derived from boehmite particles; and the second washcoat layer comprising porous micron-sized particles comprising alumina impregnated with platinum, and alumina derived from boehmite particles.
  • the boehmite particles used to derive the alumina in the first washcoat layer and the second washcoat layer can be the same or different.
  • the boehmite particles used to derive the alumina in the first washcoat layer have an average dispersed particle size of about 60 nm or less or a BET surface area of about 120 m 2 /s or more, and the boehmite particles used to derive the alumina in the second washcoat layer have an average dispersed particle size of about 150 nm or more or a BET surface area of about 250 m 2 /g or less.
  • the micron-sized particles comprising ceria in the first washcoat layer are impregnated with palladium by wet- chemistry methods.
  • the micron-sized particles comprising alumina in the second washcoat layer are impregnated with platinum by wet-chemistry methods.
  • the first washcoat layer further comprises micron-sized particles comprising alumina.
  • the first washcoat layer has a palladium loading of about 0.1 g/1 to about 0.5 g/1.
  • the first washcoat layer is substantially free of platinum.
  • the second washcoat layer has a platinum loading of about 0.2 g/1 to about 0.7 g/1. In some embodiments, the second washcoat layer is substantially free of palladium.
  • an exhaust treatment system comprising a conduit for exhaust gas and the catalyst described herein.
  • the catalyst is fluidly connected to an exhaust gas source, such as a stove, a furnace, a fireplace, or a generator.
  • an exhaust gas source such as a stove, a furnace, a fireplace, or a generator.
  • the exhaust gas source is an indoor exhaust gas source. In some embodiments, the exhaust gas source is not a vehicle. In some embodiments, the exhaust gas source burns natural gas, combustible hydrocarbon liquids, oil, kerosene, coal, or wood.
  • the exhaust gas comprises carbon monoxide, hydrocarbons (including non-methane hydrocarbons), or methane.
  • the exhaust gas is emitted by an indoor exhaust gas source, such as an indoor stove, furnace, fireplace, or generator.
  • the exhaust gas source is not a vehicle.
  • the exhaust gas source burns natural gas, combustible hydrocarbon liquids, oil, kerosene, coal, or wood.
  • a method of making a catalyst comprising (1) coating a substrate with a first washcoat composition comprising porous micron-sized particles comprising ceria, a palladium salt, and boehmite particles, or a first washcoat composition comprising porous micron-sized particles comprising ceria impregnated with palladium, and boehmite particles; and (2) coating the substrate with a second washcoat composition comprising porous micron-sized particles comprising alumina, a platinum salt, and boehmite particles, or a second washcoat composition comprising porous micron-sized particles comprising alumina impregnated with platinum, and boehmite particles.
  • the boehmite particles in the first washcoat composition and the second washcoat composition can be the same or different.
  • the method comprises drying the first washcoat composition after it has been coated onto the substrate.
  • the method comprises calcining the substrate after the first washcoat composition has been coated onto the substrate.
  • the method comprises drying the second washcoat composition after it has been coated onto the substrate.
  • the method comprises calcining the substrate after the second washcoat composition has been coated onto the substrate.
  • the substrate is coated with the first washcoat composition prior to being coated with the second washcoat composition.
  • Reference to "about” a value or parameter herein includes (and describes) variations that are directed to that value or parameter per se. For example, description referring to "about X” includes description of "X”.
  • the unit of measure "g/1" or "grams per liter” is used as a measure of density of a substance in terms of the mass of the substance in any given volume containing that substance.
  • g/1 is used to refer to the mass of solids in the washcoat or washcoat layer per the volume of the substrate.
  • an amount of material "loaded” onto a substrate is used to refer to the mass of that material per the volume of the substrate.
  • platinum loaded onto a substrate at 4.0 g/1 refers to 4.0 grams of platinum for each liter of a coated substrate.
  • a washcoat layer thickness of 100 g/1 refers to a washcoat layer having 100 grams of solids for each liter of the coated substrate.
  • platinum group metals refers to the collective name for the metals ruthenium, rhodium, palladium, osmium, iridium, and platinum.
  • a "portion" of a material is understood to mean at least some of the material and may include all of that material.
  • the word “substantially” does not exclude “completely.”
  • a composition which is “substantially free” from Y may be completely free from Y.
  • the term “substantially free” permits trace or naturally occurring impurities. It should be noted that, during fabrication, or during operation (particularly over long periods of time), small amounts of materials present in one washcoat layer may diffuse, migrate, or otherwise move into other washcoat layers. Accordingly, use of the terms “substantial absence of and “substantially free of is not to be construed as absolutely excluding minor amounts of the materials referenced. Where necessary, the word “substantially” may be omitted from the definition of the invention.
  • Treating an exhaust gas refers to having the exhaust gas proceed through an exhaust system, thereby catalyzing at least a portion of the gasses in the exhaust gas into some other chemical form prior to release into the environment.
  • a “washcoat composition” refers to a suspension of one or more solid components, such as particles, in a liquid.
  • the washcoat composition can also include one or more salts dissolved in the liquid.
  • a “washcoat layer” refers to a washcoat composition after the composition has been applied to a substrate, either before or after the washcoat composition has been dried or calcined.
  • the term "wet-chemistry method” is used herein to describe any technique whereby a solution of a metal salt is deposited on or in a material, and the metal salt is converted into a metallic form.
  • weight percentages of materials in a solution or suspension refer to the weight percentages of solids in that solution or suspension after removing liquid components.
  • Salts such as barium slats or other materials dissolved in the liquid are included as solids if the salts or other materials would be solids upon evaporation of the liquid.
  • relative weight percentages in a composition assumes that the combined total weight percentages of all components in the composition add up to 100. It is further understood that relative weight percentages of one or more components may be adjusted upwards or downwards such that the weight percent of the components in the composition combine to a total of 100, provided that the weight percent of any particular component does not fall outside the limits of the range specified for that component.
  • the methods, systems, compositions, and devices can either comprise the listed components or steps, or can “consist of or "consist essentially of the listed components or steps.
  • the system, composition, or device contains the components listed, and may contain other components which do not substantially affect the performance of the system, composition, or device, but either do not contain any other components which substantially affect the
  • any disclosed upper limit may be combinable with any disclosed lower limit to provide a range.
  • Each of these combinations of disclosed upper and lower limits are explicitly envisaged herein.
  • ranges for the amount of a particular component are given as 50 g/L - 200 g/L, and 90 g/L - 170 g/L, the ranges 50 g/L - 170 g/L and 90 g/L - 200 g/L are also envisaged.
  • the catalyst includes at least two washcoat layers coating a substrate.
  • the first washcoat layer includes micron-sized particles comprising ceria impregnated with palladium.
  • the second washcoat layer includes micron-sized particles comprising alumina impregnated with platinum.
  • Alumina derived from boehmite particles is also present in the first washcoat layer and the second washcoat layer, although the boehmite particles used to derive the boehmite in the first washcoat layer and the second layer may be the same or different (for example, different average dispersed particles size or BET surface area).
  • the first washcoat layer is disposed underneath the second washcoat layer (that is, the first washcoat layer is more proximal to the substrate than the second washcoat layer).
  • the second washcoat layer is disposed underneath the first washcoat layer. It is further contemplated that one or more additional layers can coat the substrate above or below the first washcoat layer or the second washcoat layer (including between the first washcoat layer and the second washcoat layer).
  • the micron-sized particles comprising ceria have an average diameter of about 0.5 micrometers to about 20 micrometers (such as about 1 micrometer to about 15 micrometers, about 2 micrometers to about 10 micrometers, about 3 micrometers to about 8 micrometers, or about 4 micrometers to about 6 micrometers).
  • Exemplary micron-sized particles comprising ceria are HSA20 particles, available from Grace Division, Rhodia.
  • the micron-sized particles comprising ceria are porous, which allows a high surface area to contact exhaust gas flowing through the particles.
  • the micron-sized particles comprising ceria are impregnated with palladium, for example by wet-chemistry methods.
  • a palladium salt solution can be combined with porous micron-sized particles comprising ceria, and the palladium salt can be converted into metallic palladium that impregnates the micron-sized particles.
  • the micron-sized particles comprising ceria and wetted with the palladium salt solution can be calcined (or dried and then calcined), which converts the palladium salt to the metallic palladium.
  • the palladium salt solution is free or substantially free of a platinum salt or metallic platinum.
  • Chloropalladic acid, FbPdCle, and palladium (II) nitrate, Pd(N0 3 )2 are exemplary salts that can be used to impregnate the porous micron-sized particles comprising ceria.
  • the micron-sized particles comprising ceria can be impregnated with palladium by wet-chemistry methods either before or after being combined with the other washcoat ingredients.
  • the porous micron-sized particles comprising ceria are combined with a palladium salt and calcined (with an optional drying step prior to the calcining step), thereby converting the palladium salt into metallic palladium to impregnate the micron-sized particles with the palladium.
  • micron-sized particles comprising ceria and impregnated with the palladium can then be combined with any other washcoat composition ingredients (such as boehmite or micron- sized particles comprising alumina) to form the washcoat composition, which can be coated onto the substrate.
  • washcoat composition ingredients such as boehmite or micron- sized particles comprising alumina
  • the porous micron-sized particles comprising ceria are combined with the palladium salt and the other washcoat composition ingredients (such as boehmite or micron-sized particles comprising alumina) to form the washcoat composition.
  • washcoat composition comprising the micron-sized particles comprising ceria and the palladium salt (and any other washcoat composition ingredients) is then coated onto the substrate and calcined (with an optional drying step before the calcining step), thereby converting the palladium salt, which had impregnated the micron-sized particles in the washcoat composition, into metallic palladium.
  • the micron-sized particles comprising ceria make up about 60 wt% or more (such as about 70 wt% or more, about 80 wt% or more, or about 90 wt% or more) of the solids in the first washcoat layer. In some embodiments, the micron-sized particles comprising ceria make up about 60 wt% to about 95 wt% (such as about 60 wt% to about 95 wt%, about 70 wt% to about 95 wt%, about 80 wt% to about 95 wt%, about 88 wt%, or about 89 wt%) of the solids in the first washcoat layer.
  • the first washcoat layer further comprises micron-sized particles comprising alumina.
  • the micron-sized particles comprising alumina are porous, which allows a high surface area to contact exhaust gas flowing through the particles.
  • the micron-sized particles comprising alumina can have an average diameter of about 0.5 micrometers to about 20 micrometers (such as about 1 micrometer to about 15 micrometers, about 2 micrometers to about 10 micrometers, about 3 micrometers to about 8 micrometers, or about 4 micrometers to about 6 micrometers).
  • Exemplary micron-sized particles comprising alumina are MI-386 particles, available from Grace Division, Rhodia.
  • the micron-sized particles comprising alumina are stabilized with lanthana.
  • the micron-sized particles comprising alumina can comprise about 2 wt% to about 4 wt% lanthana.
  • the micron-sized particles comprising alumina make up about 2 wt% to about 10 wt% (such as about 3 wt% to about 8 wt%, or about 4 wt% to about 6 wt%) of the solids in the first washcoat layer.
  • the micron-sized particles comprising alumina in the first washcoat layer are impregnated with palladium, for example by wet-chemistry methods.
  • the micron-sized particles comprising alumina in the first washcoat layer can be impregnated with palladium in a similar manner as the micron-sized particles comprising ceria in the first washcoat layer.
  • a palladium salt solution can be combined with porous micron-sized particles comprising alumina, and the palladium salt can be converted into metallic palladium that impregnates the micron-sized particles.
  • the micron-sized particles comprising alumina and wetted with the palladium salt solution can be calcined (or dried and then calcined), which converts the palladium salt to the metallic palladium.
  • the palladium salt solution is free or substantially free of a platinum salt or metallic platinum.
  • Chloropalladic acid, bPdCle, and palladium (II) nitrate, Pd(N0 3 )2 are exemplary salts that can be used to impregnate the porous micron-sized particles comprising alumina.
  • the micron-sized particles comprising alumina can be impregnated with palladium by wet-chemistry methods either before or after being combined with the other washcoat ingredients.
  • the porous micron-sized particles comprising alumina are combined with a palladium salt and calcined (with an optional drying step prior to the calcining step), thereby converting the palladium salt into metallic palladium to impregnate the micron-sized particles with the metallic palladium.
  • micron-sized particles comprising alumina and impregnated with the palladium can then be combined with any other washcoat composition ingredients (such as the micron- sized particles comprising ceria and impregnated with palladium) to form the washcoat composition, which can be coated onto the substrate.
  • the porous micron- sized particles comprising alumina are combined with the palladium salt and the other washcoat composition ingredients (such as boehmite or micron-sized particles comprising ceria) to form the washcoat composition.
  • the washcoat composition comprising the micron-sized particles comprising alumina and the palladium salt (and any other washcoat composition ingredients, including the micron-sized particles comprising ceria) is then coated onto the substrate and calcined (with an optional drying step before the calcining step), thereby converting the palladium salt, which had impregnated the micron-sized particles comprising ceria and the micron-size particle comprising alumina in the washcoat composition, into metallic palladium.
  • the first washcoat layer comprises alumina derived from boehmite.
  • Boehmite converts to alumina upon calcination of the boehmite. Therefore, boehmite can be included in the washcoat composition and, after coating the washcoat composition including the boehmite on the substrate, the substrate can be calcined, thereby converting the boehmite into alumina. Inclusion of the boehmite in the washcoat composition further stabilizes the washcoat layer coated on the substrate.
  • the alumina derived from boehmite in the first washcoat layer comprises about 2 wt% to about 15 wt% (such as about 4 wt% to about 14 wt%, about 5 w% to about 12 wt%, about 6 wt% to about 8 wt%, about 8 wt% to about 10 wt%, about 10 wt% to about 12 wt%, or about 1 1 wt%) of the solids in the first washcoat layer.
  • the boehmite is generally in the form of particles that can be dispersed in solution.
  • the boehmite has an average dispersed particle size of about 10 nm to about 400 nm (such as about 10 nm to about 30 nm, about 30 nm to about 60 nm, about 60 nm to about 100 nm, about 100 nm to about 150 nm, about 150 nm to about 250 nm, or about 250 nm to about 400 nm). In some embodiments, the boehmite has an averaged dispersed particle size of about 60 nm or less. In some embodiments, the boehmite has an average dispersed particle size of about 150 nm or more.
  • the average dispersed particle size of the boehmite can be measured after forming a 10 wt% boehmite dispersion in water using laser diffraction spectroscopy techniques.
  • the BET surface area of the boehmite is about 80 m 2 /g to about 300 m 2 /g (such as about 100 m 2 /g to about 260 m 2 /g, such as about 100 m 2 /g to about 140 m 2 /g, about 140 m 2 /g to about 180 m 2 /g, about 180 m 2 /g to about 220 m 2 /g, or about 220 m 2 /g to about 260 m 2 /g).
  • the BET surface area of the boehmite is about 250 m 2 /g or less (such as about 200 m 2 /g or less, or about 160 m 2 /g or less). In some embodiments, the BET surface area of the boehmite is about 120 m 2 /g or more (such as about 160 m 2 /g or more, or about 180 m 2 /g or more). The BET surface area of the boehmite is measured after calcining the boehmite at 550 °C for three hours and measuring the surface are of the resulting alumina using BET nitrogen adsorption techniques.
  • Exemplary boehmite particles that can be used to for the first washcoat layer are DISPERAL® P2 boehmite particles, available from Sasol (Hamburg, Germany).
  • DISPERAL® P2 boehmite particles have an average dispersed particle size of about 25 nm and a BET surface area of about 260 m 2 /g.
  • DISPAL® 11N7-80 boehmite particles can also or alternatively be used in the first washcoat layer.
  • the first washcoat layer has a thickness of about 100 g/1 to about 300 g/1 (such as about 100 g/1 to about 120 g/1, about 120 g/1 to about 140 g/1, about 140 g/1 to about 160 g/1, about 160 g/1 to about 180 g/1, about 180 g/1 to about 200 g/1, about 200 g/1 to about 220 g/1, about 220 g/1 to about 240 g/1, about 240 g/1 to about 270 g/1, or about 270 g/1 to about 300 g/1).
  • the first washcoat layer has a palladium loading of about 0.1 g/1 to about 0.5 g/1, (such as about 0.15 g/1 to about 0.3 g/1, or about 0.2 g/1). In some embodiments, the first washcoat layer is substantially free of platinum. In some embodiments, the first washcoat layer is substantially free of any platinum group metal other than palladium.
  • the second washcoat layer comprises micron-sized particles comprising alumina impregnated with platinum, such as by wet-chemistry methods.
  • the micron-sized particles comprising alumina in the second washcoat layer are porous, which allows a high surface area to contact exhaust gas flowing through the particles.
  • the micron- sized particles comprising alumina can have an average diameter of about 0.5 micrometers to about 20 micrometers (such as about 1 micrometer to about 15 micrometers, about 2
  • micrometers to about 10 micrometers about 3 micrometers to about 8 micrometers, or about 4 micrometers to about 6 micrometers).
  • Exemplary micron-sized particles comprising alumina are MI-386 particles, available from Grace Division, Rhodia.
  • the micron-sized particles comprising alumina are stabilized with lanthana.
  • the micron-sized particles comprising alumina can comprise about 2 wt% to about 4 wt% lanthana.
  • the micron-sized particles comprising alumina make up about 85 wt% to about 99 wt% (such as about 90 wt% to about 97 wt%, about 94 wt% to about 96 wt%, or about 95 wt%) of the solids in the second washcoat layer.
  • a platinum salt solution can be combined with porous micron- sized particles comprising alumina, and the platinum salt can be converted into metallic platinum that impregnates the micron-sized particles.
  • the micron-sized particles comprising alumina and wetted with the platinum salt solution can be calcined (or dried and then calcined), which converts the platinum salt to the metallic platinum.
  • the platinum salt solution is free or substantially free of a palladium salt or metallic palladium.
  • Chloroplatinic acid H 2 PtCl6, is an exemplary salt that can be used to impregnate the porous micron-sized particles comprising ceria.
  • the micron-sized particles comprising ceria can be impregnated with platinum by wet-chemistry methods either before or after being combined with the other washcoat ingredients used to form the second washcoat layer.
  • the porous micron-sized particles comprising alumina are combined with a platinum salt and calcined (with an optional drying step prior to the calcining step), thereby converting the platinum salt into metallic platinum to impregnate the micron-sized particles with the platinum.
  • the micron-sized particles comprising alumina and impregnated with the platinum can then be combined with any other washcoat composition ingredients (such as boehmite) to form the washcoat composition, which can be coated onto the substrate.
  • the porous micron-sized particles comprising alumina are combined with the platinum salt and the other washcoat composition ingredients (such as boehmite) to form the washcoat composition.
  • the washcoat composition comprising the micron-sized particles comprising alumina and the platinum salt (and any other washcoat composition ingredients) is then coated onto the substrate and calcined (with an optional drying step before the calcining step), thereby converting the platinum salt, which had impregnated the micron-sized particles in the washcoat composition, into metallic platinum.
  • the second washcoat layer comprises alumina derived from boehmite.
  • the alumina derived from boehmite in the second washcoat layer comprises about 1 wt% to about 10 wt% (such as about 2 wt% to about 8 wt%, about 3 w% to about 6 wt%, or about 4 wt% to about 5 wt%) of the solids in the second washcoat layer.
  • the boehmite is generally in the form of particles that can be dispersed in solution.
  • the boehmite has an average dispersed particle size of about 10 nm to about 400 nm (such as about 10 nm to about 30 nm, about 30 nm to about 60 nm, about 60 nm to about 100 nm, about 100 nm to about 150 nm, about 150 nm to about 250 nm, or about 250 nm to about 400 nm). In some embodiments, the boehmite has an averaged dispersed particle size of less than about 60 nm. In some embodiments, the boehmite has an average dispersed particle size of about 150 nm or more.
  • the average dispersed particle size of the boehmite can be measured after forming a 10 wt% boehmite dispersion in water using laser diffraction spectroscopy techniques.
  • the BET surface area of the boehmite is about 80 m 2 /g to about 300 m 2 /g (such as about 100 m 2 /g to about 260 m 2 /g, such as about 100 m 2 /g to about 140 m 2 /g, about 140 m 2 /g to about 180 m 2 /g, about 180 m 2 /g to about 220 m 2 /g, or about 220 m 2 /g to about 260 m 2 /g).
  • the BET surface area of the boehmite is about 250 m 2 /g or less (such as about 200 m 2 /g or less, or about 160 m 2 /g or less). In some embodiments, the BET surface area of the boehmite is about 120 m 2 /g or more (such as about 160 m 2 /g or more, or about 180 m 2 /g or more). The BET surface area of the boehmite is measured after calcining the boehmite at 550 °C for three hours and measuring the surface are of the resulting alumina using BET nitrogen adsorption techniques.
  • Exemplary boehmite particles that can be used to for the second washcoat layer are DISPAL® 11N7-80 boehmite particles, available from Sasol (Hamburg, Germany).
  • DISPAL® 11N7-80 boehmite particles have an average dispersed particle size of 220 nm and a BET surface area of about 100 m 2 /g.
  • DISPERAL® P2 boehmite particles can also or alternatively be used in the second washcoat layer.
  • the second washcoat layer has a thickness of about 40 g/1 to about 150 g/1 (such as about 40 g/1 to about 120 g/1, about 40 g/1 to about 100 g/1, about 50 g/1 to about 80 g/1, or about 60 g/1).
  • the second washcoat layer has a platinum loading of about 0.2 g/1 to about 0.7 g/1, ( such as about 0.3 g/1 to about 0.6 g/1, about 0.4 g/1 to about 0.5 g/1, or about 0.45 g/1).
  • the second washcoat layer is substantially free of palladium.
  • the second washcoat layer is substantially free of any platinum group metal other than platinum.
  • the catalyst has a platinum group metal loading (that is, total loading of the first washcoat layer, second washcoat layer, and any other washcoat layer coated on the substrate) of about 0.3 g/1 to about 1.2 g/1 (such as about 0.3 g/1 to about 1 g/1, about 0.4 g/1 to about 0.8 g/1, about 0.5 g/1 to about 0.7 g/1, or about 0.67 g/1).
  • the substrate preferably demonstrates good thermal stability, including resistance to thermal shock, and to which the described washcoat compositions can be affixed in a stable manner.
  • Suitable substrates include, but are not limited to, substrates formed from cordierite or other ceramic materials, and substrates formed from metal.
  • the substrates may include a honeycomb structure, which provides numerous channels and results in a high surface area. The high surface area of the coated substrate with its applied washcoat layers in the catalytic converter provides for effective treatment of the exhaust gas flowing through the catalyst.
  • the substrate has a thickness (i.e., dimension in the direction of gas flow through the substrate) of about 0.5 cm to about 6 cm (for example, about 1 cm to about 4 cm, about 1.5 cm to about 3 cm, or about 2 cm).
  • the transverse profile (that is, the profile of the substrate transverse or perpendicular relative to the gas flow) of the substrate can be square, rectangular, circular, oval, or any other suitable shape.
  • the transverse profile is about 100 cm 2 to about 600 cm 2 (such as about 100 cm 2 to about 400 cm 2 , about 150 cm 2 to about 300 cm 2 , or about 175 cm 2 to about 220 cm 2 ).
  • the transverse profile is rectangular with a length of about 15 cm to about 30 cm (such as about 17 cm to about 28 cm, about 20 cm to about 25 cm, or about 22.5 cm) and a width of about 5 cm to about 12 cm (such as about 7 cm to about 10 cm, or about 8.5 cm).
  • a catalyst comprises a substrate coated with a first washcoat layer and a second washcoat layer; the first washcoat layer comprising porous micron- sized particles comprising ceria impregnated with palladium, and alumina derived from boehmite particles; and the second washcoat layer comprising porous micron-sized particles comprising alumina impregnated with platinum, and alumina derived from boehmite particles.
  • the first washcoat layer further comprises porous micron-sized particles comprising alumina.
  • the porous micron-sized particles comprising alumina are impregnated with palladium by wet-chemistry methods.
  • the porous micron-sized particles in the first washcoat layer make up about 2 wt% to about 10 wt% of the solids in the first washcoat layer. In some embodiments, the alumina derived from boehmite in the first washcoat layer makes up about 2 wt% to about 15 wt% of the solids in the first washcoat layer. In some embodiments, the alumina derived from boehmite in the second washcoat layer makes up about 1 wt% to about 8 wt% of the solids in the second washcoat layer. In some embodiments, the first washcoat layer has a thickness of about 100 g/1 to about 300 g/1.
  • the second washcoat layer has a thickness of about 40 g/1 to about 150 g/1.
  • the catalyst has a platinum group metal loading of about 0.3 g/1 to about 1.2 g/1 (such as about 0.5 g/1 to about 0.8 g/1).
  • the porous micron-sized particles comprising ceria in the first washcoat layer make up about 60 wt% to about 95 wt% of the solids in the first washcoat layer.
  • the substrate is about 0.5 cm to about 6 cm thick. In some embodiments, the substrate has a transverse profile of about 100 cm 2 to about 600 cm 2 .
  • a catalyst comprises a substrate coated with a first washcoat layer and a second washcoat layer; the first washcoat layer comprising porous micron- sized particles comprising ceria impregnated with palladium by wet-chemistry methods, and alumina derived from boehmite particles; and the second washcoat layer comprising porous micron-sized particles comprising alumina impregnated with platinum by wet-chemistry methods, and alumina derived from boehmite particles.
  • the first washcoat layer further comprises porous micron-sized particles comprising alumina.
  • the porous micron-sized particles comprising alumina are impregnated with palladium by wet-chemistry methods.
  • the porous micron-sized particles in the first washcoat layer make up about 2 wt% to about 10 wt% of the solids in the first washcoat layer.
  • the alumina derived from boehmite in the first washcoat layer makes up about 2 wt% to about 15 wt% of the solids in the first washcoat layer.
  • the alumina derived from boehmite in the second washcoat layer makes up about 1 wt% to about 8 wt% of the solids in the second washcoat layer.
  • the first washcoat layer has a thickness of about 100 g/1 to about 300 g/1. In some embodiments, the second washcoat layer has a thickness of about 40 g/1 to about 150 g/1. In some embodiments, the catalyst has a platinum group metal loading of about 0.3 g/1 to about 1.2 g/1 (such as about 0.5 g/1 to about 0.8 g/1). In some embodiments, the porous micron-sized particles comprising ceria in the first washcoat layer make up about 60 wt% to about 95 wt% of the solids in the first washcoat layer. In some embodiments, the substrate is about 0.5 cm to about 6 cm thick. In some embodiments, the substrate has a transverse profile of about 100 cm 2 to about 600 cm 2 .
  • a catalyst comprises a substrate coated with a first washcoat layer and a second washcoat layer; the first washcoat layer comprising porous micron- sized particles comprising ceria impregnated with palladium by wet-chemistry methods, and alumina derived from boehmite particles having an average dispersed particle size of about 60 nm or less (such as about 10 nm to about 30 nm); and the second washcoat layer comprising porous micron-sized particles comprising alumina impregnated with platinum by wet-chemistry methods, and alumina derived from boehmite particles.
  • the first washcoat layer further comprises porous micron-sized particles comprising alumina.
  • the porous micron-sized particles comprising alumina are impregnated with palladium by wet-chemistry methods.
  • the porous micron-sized particles in the first washcoat layer make up about 2 wt% to about 10 wt% of the solids in the first washcoat layer.
  • the alumina derived from boehmite in the first washcoat layer makes up about 2 wt% to about 15 wt% of the solids in the first washcoat layer.
  • the alumina derived from boehmite in the second washcoat layer makes up about 1 wt% to about 8 wt% of the solids in the second washcoat layer.
  • the first washcoat layer has a thickness of about 100 g/1 to about 300 g/1. In some embodiments, the second washcoat layer has a thickness of about 40 g/1 to about 150 g/1. In some embodiments, the catalyst has a platinum group metal loading of about 0.3 g/1 to about 1.2 g/1 (such as about 0.5 g/1 to about 0.8 g/1). In some embodiments, the porous micron-sized particles comprising ceria in the first washcoat layer make up about 60 wt% to about 95 wt% of the solids in the first washcoat layer. In some embodiments, the substrate is about 0.5 cm to about 6 cm thick. In some embodiments, the substrate has a transverse profile of about 100 cm 2 to about 600 cm 2 .
  • a catalyst comprises a substrate coated with a first washcoat layer and a second washcoat layer; the first washcoat layer comprising porous micron- sized particles comprising ceria impregnated with palladium by wet-chemistry methods, and alumina derived from boehmite particles; and the second washcoat layer comprising porous micron-sized particles comprising alumina impregnated with platinum by wet-chemistry methods, and alumina derived from boehmite particles; wherein the first washcoat layer has a palladium loading of about 0.1 g/1 to about 0.5 g/1, and the second washcoat layer has a platinum group loading of about 0.2 g/1 to about 0.7 g/1.
  • the first washcoat layer further comprises porous micron-sized particles comprising alumina.
  • the porous micron-sized particles comprising alumina are impregnated with palladium by wet- chemistry methods.
  • the porous micron-sized particles in the first washcoat layer make up about 2 wt% to about 10 wt% of the solids in the first washcoat layer.
  • the alumina derived from boehmite in the first washcoat layer makes up about 2 wt% to about 15 wt% of the solids in the first washcoat layer.
  • the alumina derived from boehmite in the second washcoat layer makes up about 1 wt% to about 8 wt% of the solids in the second washcoat layer.
  • the first washcoat layer has a thickness of about 100 g/1 to about 300 g/1.
  • the second washcoat layer has a thickness of about 40 g/1 to about 150 g/1.
  • the catalyst has a platinum group metal loading of about 0.3 g/1 to about 1.2 g/1 (such as about 0.5 g/1 to about 0.8 g/1).
  • the porous micron-sized particles comprising ceria in the first washcoat layer make up about 60 wt% to about 95 wt% of the solids in the first washcoat layer.
  • the substrate is about 0.5 cm to about 6 cm thick. In some embodiments, the substrate has a transverse profile of about 100 cm 2 to about 600 cm 2 .
  • a catalyst comprises a substrate coated with a first washcoat layer and a second washcoat layer; the first washcoat layer comprising porous micron- sized particles comprising ceria impregnated with palladium by wet-chemistry methods, and alumina derived from boehmite particles having an average dispersed particle size of about 60 nm or less (such as about 10 nm to about 30 nm); and the second washcoat layer comprising porous micron-sized particles comprising alumina impregnated with platinum by wet-chemistry methods, and alumina derived from boehmite particles; wherein the first washcoat layer has a palladium loading of about 0.1 g/1 to about 0.5 g/1, and the second washcoat layer has a platinum group loading of about 0.2 g/1 to about 0.7 g/1.
  • the first washcoat layer further comprises porous micron-sized particles comprising alumina.
  • the porous micron-sized particles comprising alumina are impregnated with palladium by wet- chemistry methods.
  • the porous micron-sized particles in the first washcoat layer make up about 2 wt% to about 10 wt% of the solids in the first washcoat layer.
  • the alumina derived from boehmite in the first washcoat layer makes up about 2 wt% to about 15 wt% of the solids in the first washcoat layer.
  • the alumina derived from boehmite in the second washcoat layer makes up about 1 wt% to about 8 wt% of the solids in the second washcoat layer.
  • the first washcoat layer has a thickness of about 100 g/1 to about 300 g/1.
  • the second washcoat layer has a thickness of about 40 g/1 to about 150 g/1.
  • the catalyst has a platinum group metal loading of about 0.3 g/1 to about 1.2 g/1 (such as about 0.5 g/1 to about 0.8 g/1).
  • the porous micron-sized particles comprising ceria in the first washcoat layer make up about 80 wt% to about 95 wt% of the solids in the first washcoat layer.
  • the substrate is about 0.5 cm to about 6 cm thick. In some embodiments, the substrate has a transverse profile of about 100 cm 2 to about 600 cm 2 .
  • a catalyst comprises a substrate coated with a first washcoat layer and a second washcoat layer; the first washcoat layer comprising porous micron- sized particles comprising ceria impregnated with palladium by wet-chemistry methods, and alumina derived from boehmite particles having an average dispersed particle size of about 60 nm or less (such as about 10 nm to about 30 nm); and the second washcoat layer comprising porous micron-sized particles comprising alumina impregnated with platinum by wet-chemistry methods, and alumina derived from boehmite particles having an average dispersed particle size of about 150 nm or more (such as about 180 nm to about 240 nm).
  • the first washcoat layer further comprises porous micron-sized particles comprising alumina.
  • the porous micron-sized particles comprising alumina are impregnated with palladium by wet-chemistry methods.
  • the porous micron-sized particles in the first washcoat layer make up about 2 wt% to about 10 wt% of the solids in the first washcoat layer.
  • the alumina derived from boehmite in the first washcoat layer makes up about 2 wt% to about 15 wt% of the solids in the first washcoat layer.
  • the alumina derived from boehmite in the second washcoat layer makes up about 1 wt% to about 8 wt% of the solids in the second washcoat layer.
  • the first washcoat layer has a thickness of about 100 g/1 to about 300 g/1.
  • the second washcoat layer has a thickness of about 40 g/1 to about 150 g/1.
  • the catalyst has a platinum group metal loading of about 0.3 g/1 to about 1.2 g/1 (such as about 0.5 g/1 to about 0.8 g/1).
  • the porous micron-sized particles comprising ceria in the first washcoat layer make up about 60 wt% to about 95 wt% of the solids in the first washcoat layer.
  • the substrate is about 0.5 cm to about 6 cm thick. In some embodiments, the substrate has a transverse profile of about 100 cm 2 to about 600 cm 2 .
  • a catalyst comprises a substrate coated with a first washcoat layer and a second washcoat layer; the first washcoat layer comprising porous micron- sized particles comprising ceria impregnated with palladium by wet-chemistry methods, and alumina derived from boehmite particles having an average dispersed particle size of about 60 nm or less (such as about 10 nm to about 30 nm); and the second washcoat layer comprising porous micron-sized particles comprising alumina impregnated with platinum by wet-chemistry methods, and alumina derived from boehmite particles having an average dispersed particle size of about 150 nm or more (such as about 180 nm to about 240 nm) ; wherein the first washcoat layer has a palladium loading of about 0.1 g/1 to about 0.5 g/1, and the second washcoat layer has a platinum group loading of about 0.2 g/1 to about 0.7 g/1.
  • the first washcoat layer further comprises porous micron-sized particles comprising alumina.
  • the porous micron-sized particles comprising alumina are impregnated with palladium by wet-chemistry methods.
  • the porous micron-sized particles in the first washcoat layer make up about 2 wt% to about 10 wt% of the solids in the first washcoat layer.
  • the alumina derived from boehmite in the first washcoat layer makes up about 2 wt% to about 15 wt% of the solids in the first washcoat layer.
  • the alumina derived from boehmite in the second washcoat layer makes up about 1 wt% to about 8 wt% of the solids in the second washcoat layer.
  • the first washcoat layer has a thickness of about 100 g/1 to about 300 g/1.
  • the second washcoat layer has a thickness of about 40 g/1 to about 150 g/1.
  • the catalyst has a platinum group metal loading of about 0.3 g/1 to about 1.2 g/1 (such as about 0.5 g/1 to about 0.8 g/1).
  • the porous micron-sized particles comprising ceria in the first washcoat layer make up about 60 wt% to about 95 wt% of the solids in the first washcoat layer.
  • the substrate is about 0.5 cm to about 6 cm thick. In some embodiments, the substrate has a transverse profile of about 100 cm 2 to about 600 cm 2 .
  • a catalyst comprises a substrate coated with a first washcoat layer and a second washcoat layer; the first washcoat layer comprising about 85 wt% to about 90 wt% porous micron-sized particles comprising ceria impregnated with palladium by wet-chemistry methods, about 3 wt% to about 7 wt% porous micron-sized particles comprising alumina, and about 5 wt% to about 10 wt% alumina derived from boehmite particles having an average dispersed particle size of about 60 nm or less (such as about 10 nm to about 30 nm); and the second washcoat layer comprising about 90 wt% to about 99 wt% porous micron-sized particles comprising alumina impregnated with platinum by wet-chemistry methods, and about 1 wt% to about 10 wt% or about 1 wt% to about 8 wt% alumina derived from boehmite particles having an average dispersed particle
  • the porous micron-sized particles comprising alumina are impregnated with palladium by wet-chemistry methods.
  • the first washcoat layer has a thickness of about 100 g/1 to about 300 g/1.
  • the second washcoat layer has a thickness of about 40 g/1 to about 150 g/1.
  • the catalyst has a platinum group metal loading of about 0.3 g/1 to about 1.2 g/1 (such as about 0.5 g/1 to about 0.8 g/1).
  • a method of making a catalyst comprises (1) coating a substrate with A) a first washcoat composition comprising porous micron-sized particles comprising ceria, a palladium salt, andboehmite particles; or B) a first washcoat composition comprising porous micron-sized particles comprising ceria impregnated with palladium, and boehmite particles; and (2) coating the substrate with C) a second washcoat composition comprising porous micron-sized particles comprising alumina, a platinum salt, and boehmite particles; or D) a second washcoat composition comprising porous micron-sized particles comprising alumina impregnated with platinum, andboehmite particles.
  • the first and second washcoat compositions can be selected from the pairs A) and C), A) and D), B) and C), or B) and D).
  • the boehmite particles in the first washcoat composition and the second washcoat composition may be the same or different (for example, different average dispersed particles size or BET surface area).
  • the first washcoat composition further comprises micron-sized particles comprising alumina.
  • the substrate is coated with the first washcoat composition before the substrate is coated with the second washcoat composition.
  • the first washcoat composition can be applied to the substrate (which may already have one or more previously-applied washcoat layers) by coating the substrate with a washcoat composition, for example by dip coating the substrate. Excess washcoat composition can be blown off the substrate (and optionally collecting and recycling the excess washcoat blown off the substrate). Once coated with a first washcoat composition, the coated substrate can be dried and/or calcined. The substrate can be coated in the second washcoat compositions, for example by dip coating the substrate. Excess washcoat composition can be blown off the substrate (and optionally collecting and recycling the excess washcoat blown off the substrate). Once coated with the second washcoat composition, the coated substrate can be dried and/or calcined. In some embodiments one or more additional washcoat compositions are coated onto the substrate, either before or after the application of the first washcoat composition or the second washcoat composition.
  • Drying of the washcoat layers can be performed at room temperature or elevated temperature (for example, from about 30°C to about 95°C, preferably about 60°C to about 70°C), at atmospheric pressure or at reduced pressure (for example, from about 1 pascal to about 90,000 pascal, or from about 7.5 mTorr to about 675 Torr), in ambient atmosphere or under an inert atmosphere (such as nitrogen or argon), and with or without passing a stream of gas over the substrate (for example, dry air, dry nitrogen gas or dry argon gas).
  • the drying process is a hot-drying process.
  • a hot drying process includes any way to remove the solvent at a temperature greater than room temperature, but at a temperature below a standard calcining temperature.
  • the drying process may be a flash drying process, involving the rapid evaporation of moisture from the substrate via a sudden reduction in pressure or by placing the substrate in an updraft of warm air. It is contemplated that other drying processes may also be used.
  • the washcoat layer is dried for about 2 hours to about 48 hours (such as about 4 hours to about 36 hours, about 6 hours to about 24 hours, or about 8 hours to about 12 hours).
  • the washcoat may then be calcined onto the substrate. Calcining takes place at elevated temperatures, such as from 400°C to about 700°C, preferably about 500°C to about 600°C, more preferably at about 540°C to about 560°C or at about 550°C. In some embodiments, calcining occurs at atmospheric pressure. In some embodiments, calcining occurs in ambient atmosphere, an oxidizing atmosphere, a non-oxidizing atmosphere, or a reducing atmosphere. In some embodiments, the washcoat layer is calcined for about 1 hour to about 24 hours (such as about 2 hours to about 18 hours, about 3 hours to about 12 hours, about 4 hours to about 8 hours, or about 6 hours).
  • FIG. 1 A illustrates one method of forming the catalyst in accordance with some embodiments of the present invention.
  • the method comprises coating the substrate with a first washcoat composition to form a first washcoat layer, and coating the substrate with a second washcoat composition to form a second washcoat layer.
  • a first washcoat composition is applied to the substrate to from the first washcoat layer.
  • the first washcoat composition comprises micron-sized particles comprising ceria impregnated with palladium.
  • the first washcoat composition comprises micron-sized particles comprising ceria and a palladium salt.
  • the first washcoat composition can further include micron-sized particles comprising alumina and/or boehmite particles.
  • the boehmite is in the form of particles with an average dispersed particle size of about 60 nm or less (such as about 10 nm to about 30 nm). In some embodiments, the boehmite has a BET surface area of about 180 m 2 /s or more (such as about 220 m 2 /g to about 300 m 2 /g).
  • a first drying process is performed on the substrate. Examples of such drying processes include, but are not limited to, a hot-drying process, or a flash drying process.
  • a first calcining process is performed on the substrate.
  • the second washcoat composition is applied to the substrate to coat the substrate with a second washcoat layer on top of the first washcoat layer.
  • the second washcoat composition comprises micron-sized particles comprising alumina impregnated with platinum.
  • the second washcoat composition comprises micron-sized particles comprising alumina and a platinum salt.
  • the second washcoat composition further comprises boehmite particles.
  • the boehmite is in the form of particles with an average dispersed particle size of about 150 nm or more (such as about 180 nm to about 240 nm).
  • the boehmite has a BET surface area of about 160 m 2 /g or less (such as about 80 m 2 /g to about 140 m 2 /g.
  • a second drying process is performed on the substrate. Examples of such drying processes include, but are not limited to, a hot-drying process, or a flash drying process.
  • a first calcining process is performed on the substrate.
  • FIG. IB illustrates one embodiment of a catalyst including a substrate 135 coated with the first washcoat layer 140 and the second washcoat layer 145.
  • Washcoat compositions are prepared by suspending the designated materials in an aqueous solution.
  • the pH of the resulting suspension can be adjusted to between about 2 and about 7 (such as between about 3 and about 5, or to about 4).
  • the viscosity can also be adjusted, if desired, for example by adding cellulose, cornstarch, or other rheology modifiers to the washcoat composition. In some embodiments, the viscosity is adjusted to between about 300 cP and about 1200 cP.
  • the first washcoat composition comprises micron-sized particles comprising ceria impregnated with palladium, for example by wet-chemistry methods. In some embodiments, the first washcoat composition further comprises boehmite particles. In some embodiments, the first washcoat composition further comprises micron-sized particles comprising alumina. In some embodiments, the first washcoat composition is substantially free of platinum or a platinum salt.
  • the first washcoat composition comprises micron-sized particles comprising ceria and palladium salt. In some embodiments, the first washcoat composition further comprises boehmite particles. In some embodiments, the first washcoat composition further comprises micron-sized particles comprising alumina. In some
  • the first washcoat composition is substantially free of platinum or a platinum salt.
  • the micron-sized particles comprising ceria in the first washcoat composition have an average diameter of about 0.5 micrometers to about 20 micrometers (such as about 1 micrometer to about 15 micrometers, about 2 micrometers to about 10 micrometers, about 3 micrometers to about 8 micrometers, or about 4 micrometers to about 6 micrometers).
  • Exemplary micron-sized particles comprising ceria are HSA20 particles, available from Grace Division, Rhodia.
  • the micron-sized particles comprising ceria are porous, which allows a high surface area to contact exhaust gas flowing through the particles.
  • the micron-sized particles comprising ceria make up about 60 wt% or more (such as about 70 wt% or more, about 80 wt% or more, or about 90 wt% or more) of the solids in the first washcoat composition. In some embodiments, the micron-sized particles comprising ceria make up about 60 wt% to about 95 wt% (such as about 60 wt% to about 95 wt%, about 70 wt% to about 95 wt%, about 80 wt% to about 95 wt%, about 88 wt%, or about 89 wt%) of the solids in the first washcoat composition.
  • the first washcoat composition further includes micron- sized particles comprising alumina.
  • the micron-sized particles comprising alumina are porous, which allows a high surface area to contact exhaust gas flowing through the particles.
  • the micron-sized particles comprising alumina can have an average diameter of about 0.5 micrometers to about 20 micrometers (such as about 1 micrometer to about 15 micrometers, about 2 micrometers to about 10 micrometers, about 3 micrometers to about 8 micrometers, or about 4 micrometers to about 6 micrometers).
  • Exemplary micron-sized particles comprising alumina are MI-386 particles, available from Grace Division, Rhodia.
  • the micron-sized particles comprising alumina are stabilized with lanthana.
  • the micron-sized particles comprising alumina can comprise about 2 wt% to about 4 wt% lanthana.
  • the micron-sized particles comprising alumina make up about 2 wt% to about 10 wt% (such as about 3 wt% to about 8 wt%, or about 4 wt% to about 6 wt%) of the solids in the first washcoat composition.
  • the first washcoat composition comprises boehmite particles.
  • the boehmite in the first washcoat composition comprises about 2 wt% to about 15 wt% (such as about 4 wt% to about 14 wt%, about 5 w% to about 12 wt%, about 6 wt% to about 8 wt%, about 8 wt% to about 10 wt%, about 10 wt% to about 12 wt%, or about 1 1 wt%) of the solids in the first washcoat composition.
  • the boehmite is generally in the form of particles that can be dispersed in the washcoat composition.
  • the boehmite has an average dispersed particle size of about 10 nm to about 400 nm (such as about 10 nm to about 30 nm, about 30 nm to about 60 nm, about 60 nm to about 100 nm, about 100 nm to about 150 nm, about 150 nm to about 250 nm, or about 250 nm to about 400 nm). In some embodiments, the boehmite has an averaged dispersed particle size of less than about 60 nm. In some embodiments, the boehmite has an average dispersed particle size of about 150 nm or more.
  • the BET surface area of the boehmite is about 80 m 2 /g to about 300 m 2 /g (such as about 100 m 2 /g to about 260 m 2 /g, such as about 100 m 2 /g to about 140 m 2 /g, about 140 m 2 /g to about 180 m 2 /g, about 180 m 2 /g to about 220 m 2 /g, or about 220 m 2 /g to about 260 m 2 /g). In some embodiments, the BET surface area of the boehmite is about 250 m 2 /g or less (such as about 200 m 2 /g or less, or about 160 m 2 /g or less).
  • the BET surface area of the boehmite is about 120 m 2 /g or more (such as about 160 m 2 /g or more, or about 180 m 2 /g or more).
  • Exemplary boehmite particles that can be used for the first washcoat composition are DISPERAL® P2 boehmite particles, available from Sasol (Hamburg,
  • the first washcoat composition is coated onto the substrate to obtain a thickness of about 100 g/1 to about 300 g/1 (such as about 100 g/1 to about 120 g/1, about 120 g/1 to about 140 g/1, about 140 g/1 to about 160 g/1, about 160 g/1 to about 180 g/1, about 180 g/1 to about 200 g/1, about 200 g/1 to about 220 g/1, about 220 g/1 to about 240 g/1, about 240 g/1 to about 270 g/1, or about 270 g/1 to about 300 g/1).
  • the first washcoat composition is coated onto the substrate to obtain a palladium loading of about 0.1 g/1 to about 0.5 g/1, (such as about 0.15 g/1 to about 0.3 g/1, or about 0.2 g/1).
  • the first washcoat composition is substantially free of platinum.
  • the first washcoat composition is substantially free of any platinum group metal other than palladium.
  • the first washcoat composition comprises micron-sized particles comprising ceria impregnated with palladium.
  • the first washcoat composition further comprises boehmite particles.
  • the micron-sized particles comprising ceria makes up about 85 wt% to about 95 wt% of the solids in the first washcoat composition. In some embodiments, the boehmite makes up about 5 wt% to about 15 wt% of the solids in the first washcoat composition. In some embodiments, the boehmite has an average dispersed particle size of about 10 nm to about 30 nm. In some embodiments, the boehmite has an average BET surface area of 120 m 2 /g or more (such as about 220 m 2 /g to about 300 m 2 /g).
  • the first washcoat composition is coated onto the substrate at a thickness of about 100 g/1 to about 300 g/1. In some embodiments, the first washcoat composition is coated onto the substrate to obtain a palladium loading of about 0.1 g/1 to about 0.5 g/1.
  • the first washcoat composition comprises micron-sized particles comprising ceria impregnated with palladium, boehmite, and micron-sized particles comprising alumina.
  • the micron-sized particles comprising ceria makes up about 60 wt% to about 95 wt% of the solids in the first washcoat composition.
  • the boehmite makes up about 5 wt% to about 15 wt% of the solids in the first washcoat composition.
  • the boehmite has an average dispersed particle size of about 10 nm to about 30 nm.
  • the boehmite has an average BET surface area of about 120 m 2 /e or more (such as about 220 m 2 /g to about 300 m 2 /g).
  • the micron-sized particles comprising alumina make up about 2 wt% to about 10 wt% of the solids in the first washcoat composition.
  • the first washcoat composition is coated onto the substrate at a thickness of about 100 g/1 to about 300 g/1. In some embodiments, the first washcoat composition is coated onto the substrate to obtain a palladium loading of about 0.1 g/1 to about 0.5 g/1.
  • the first washcoat composition comprises micron-sized particles comprising ceria and a palladium salt.
  • the first washcoat composition further comprises boehmite particles.
  • the micron-sized particles comprising ceria makes up about 60 wt% to about 95 wt% of the solids in the first washcoat composition.
  • the boehmite makes up about 5 wt% to about 15 wt% of the solids in the first washcoat composition.
  • the boehmite has an average dispersed particle size of about 10 nm to about 30 nm.
  • the boehmite has an average BET surface area of about 120 m 2 /g or more (such as about 220 m 2 /g to about 300 m 2 /g).
  • the first washcoat composition is coated onto the substrate at a thickness of about 100 g/1 to about 300 g/1. In some embodiments, the first washcoat composition is coated onto the substrate to obtain a palladium loading of about 0.1 g/1 to about 0.5 g/1.
  • the first washcoat composition comprises micron-sized particles comprising ceria, a palladium salt, boehmite, and micron-sized particles comprising alumina.
  • the micron-sized particles comprising ceria makes up about 60 wt% to about 95 wt% of the solids in the first washcoat composition.
  • the boehmite makes up about 5 wt% to about 15 wt% of the solids in the first washcoat composition.
  • the boehmite has an average dispersed particle size of about 10 nm to about 30 nm.
  • the boehmite has an average BET surface area of about 120 m 2 /g or more (such as about 220 m 2 /g to about 300 m 2 /g).
  • the micron- sized particles comprising alumina make up about 2 wt% to about 10 wt% of the solids in the first washcoat composition.
  • the first washcoat composition is coated onto the substrate at a thickness of about 100 g/1 to about 300 g/1. In some embodiments, the first washcoat composition is coated onto the substrate to obtain a palladium loading of about 0.1 g/1 to about 0.5 g/1.
  • the second washcoat composition comprises micron-sized particles comprising alumina impregnated with platinum, for example by wet chemistry methods. In some embodiments, the second washcoat composition further comprises boehmite particles. In some embodiments, the second washcoat composition is substantially free of palladium or a palladium salt.
  • the second washcoat composition comprises micron-sized particles comprising alumina and a platinum salt. In some embodiments, the second washcoat composition further comprises boehmite particles. In some embodiments, the second washcoat composition is substantially free of palladium or a palladium salt.
  • the micron-sized particles comprising alumina can have an average diameter of about 0.5 micrometers to about 20 micrometers (such as about 1 micrometer to about 15 micrometers, about 2 micrometers to about 10 micrometers, about 3 micrometers to about 8 micrometers, or about 4 micrometers to about 6 micrometers).
  • Exemplary micron-sized particles comprising alumina are MI-386 particles, available from Grace Division, Rhodia.
  • the micron-sized particles comprising alumina are stabilized with lanthana.
  • the micron-sized particles comprising alumina can comprise about 2 wt% to about 4 wt% lanthana.
  • the micron-sized particles comprising alumina make up about 85 wt% to about 99 wt% (such as about 90 wt% to about 97 wt%, about 94 wt% to about 96 wt%, or about 95 wt%) of the solids in the second washcoat composition.
  • the second washcoat composition comprises boehmite particles.
  • the boehmite in the second washcoat composition makes up about 1 wt% to about 10 wt% (such as about 2 wt% to about 8 wt%, about 3 w% to about 6 wt%, or about 4 wt% to about 5 wt%) of the solids in the second washcoat composition.
  • the boehmite is generally in the form of particles that can be dispersed in the composition.
  • the boehmite has an average dispersed particle size of about 10 nm to about 400 nm (such as about 10 nm to about 30 nm, about 30 nm to about 60 nm, about 60 nm to about 100 nm, about 100 nm to about 150 nm, about 150 nm to about 250 nm, or about 250 nm to about 400 nm). In some embodiments, the boehmite has an averaged dispersed particle size of less than about 60 nm. In some embodiments, the boehmite has an average dispersed particle size of about 150 nm or more.
  • the BET surface area of the boehmite is about 80 m 2 /g to about 300 m 2 /g (such as about 100 m 2 /g to about 260 m 2 /g, such as about 100 m 2 /g to about 140 m 2 /g, about 140 m 2 /g to about 180 m 2 /g, about 180 m 2 /g to about 220 m 2 /g, or about 220 m 2 /g to about 260 m 2 /g). In some embodiments, the BET surface area of the boehmite is about 250 m 2 /g or less (such as about 200 m 2 /g or less, or about 160 m 2 /g or less).
  • the BET surface area of the boehmite is about 120 m 2 /g or more (such as about 160 m 2 /g or more, or about 180 m 2 /g or more).
  • Exemplary boehmite particles that can be used for the second washcoat composition are DISPAL® 11N7-80 boehmite particles, available from Sasol (Hamburg, Germany).
  • DISPAL® 1 1N7-80 boehmite particles have an average dispersed particle size of 220 nm and a BET surface area of about 100 m 2 /g.
  • the second washcoat composition comprises micron-sized particles comprising alumina impregnated with platinum.
  • the second washcoat composition further comprises boehmite particles.
  • the micron- sized particles comprising alumina makes up about 90 wt% to about 99 wt% of the solids in the first washcoat composition.
  • the boehmite makes up about 1 wt% to about 10 wt% of the solids in the first washcoat composition.
  • the boehmite has an average dispersed particle size of about 150 nm to about 250 nm.
  • the boehmite has an average BET surface area of about 250 m 2 /g or less (such as about 160 m 2 /g or less, or about 80 m 2 /g to about 140 m 2 /g).
  • the second washcoat composition is coated onto the substrate at a thickness of about 40 g/1 to about 150 g/1. In some embodiments, the second washcoat composition is coated onto the substrate to obtain a platinum loading of about 0.2 g/1 to about 0.7 g/1.
  • a method of making a catalyst comprises (1) coating a substrate with a first washcoat composition comprising porous micron-sized particles comprising ceria, a palladium salt, and boehmite particles, or comprising porous micron-sized particles comprising ceria impregnated with palladium, and boehmite particles; and (2) coating the substrate with a second washcoat composition comprising porous micron-sized particles comprising alumina, a platinum salt, and boehmite particles, or comprising porous micron-sized particles comprising alumina impregnated with platinum, and boehmite particles.
  • the boehmite particles in the first washcoat composition make up about 2 wt% to about 15 wt% of the solids in the first washcoat composition. In some embodiments, the boehmite particles in the second washcoat composition make up about 1 wt% to about 8 wt% of the solids in the second washcoat composition. In some embodiments, the first washcoat composition is coated onto the substrate at a thickness of about 100 g/1 to about 300 g/1 of solids. In some embodiments, the second washcoat composition is coated onto the substrate at a thickness of about 40 g/1 to about 150 g/1 of solids.
  • the micron-sized particles comprising ceria make up about 60 wt% to about 95 wt% of the solids in the first washcoat composition. In some embodiments, the micron-sized particles comprising alumina make up about 85 wt% to about 99 wt% of the solids in the second washcoat composition. In some embodiments, the porous micron-sized particles comprising ceria in the first washcoat layer make up about 60 wt% to about 95 wt% of the solids in the first washcoat layer. In some embodiments, the substrate is about 0.5 cm to about 6 cm thick. In some embodiments, the substrate has a transverse profile of about 100 cm 2 to about 600 cm 2 .
  • a method of making a catalyst comprises (1) coating a substrate with a first washcoat composition comprising porous micron-sized particles comprising ceria, a palladium salt, and boehmite particles; and (2) coating the substrate with a second washcoat composition comprising porous micron-sized particles comprising alumina, a platinum salt, and boehmite particles.
  • the boehmite particles in the first washcoat composition make up about 2 wt% to about 15 wt% of the solids in the first washcoat composition.
  • the boehmite particles in the second washcoat composition make up about 1 wt% to about 8 wt% of the solids in the second washcoat composition.
  • the first washcoat composition is coated onto the substrate at a thickness of about 100 g/1 to about 300 g/1 of solids.
  • the second washcoat composition is coated onto the substrate at a thickness of about 40 g/1 to about 150 g/1 of solids.
  • the micron-sized particles comprising ceria make up about 60 wt% to about 95 wt% of the solids in the first washcoat composition.
  • the micron-sized particles comprising alumina make up about 85 wt% to about 99 wt% of the solids in the second washcoat composition.
  • the porous micron-sized particles comprising ceria in the first washcoat layer make up about 60 wt% to about 95 wt% of the solids in the first washcoat layer.
  • the substrate is about 0.5 cm to about 6 cm thick. In some embodiments, the substrate has a transverse profile of about 100 cm 2 to about 600 cm 2 .
  • a method of making a catalyst comprises (1) coating a substrate with a first washcoat composition comprising porous micron-sized particles comprising ceria impregnated with palladium, and boehmite particles; and (2) coating the substrate with a second washcoat composition comprising porous micron-sized particles comprising alumina
  • the boehmite particles in the first washcoat composition make up about 2 wt% to about 15 wt% of the solids in the first washcoat composition. In some embodiments, the boehmite particles in the second washcoat composition make up about 1 wt% to about 8 wt% of the solids in the second washcoat composition. In some embodiments, the first washcoat composition is coated onto the substrate at a thickness of about 100 g/1 to about 300 g/1 of solids. In some embodiments, the second washcoat composition is coated onto the substrate at a thickness of about 40 g/1 to about 150 g/1 of solids.
  • the micron-sized particles comprising ceria make up about 60 wt% to about 95 wt% of the solids in the first washcoat composition. In some embodiments, the micron-sized particles comprising alumina make up about 85 wt% to about 99 wt% of the solids in the second washcoat composition. In some embodiments, the porous micron-sized particles comprising ceria in the first washcoat layer make up about 60 wt% to about 95 wt% of the solids in the first washcoat layer. In some embodiments, the substrate is about 0.5 cm to about 6 cm thick. In some embodiments, the substrate has a transverse profile of about 100 cm 2 to about 600 cm 2.
  • a method of making a catalyst comprises (1) coating a substrate with a first washcoat composition comprising porous micron-sized particles comprising ceria, a palladium salt, and boehmite particles, or comprising porous micron-sized particles comprising ceria impregnated with palladium, and boehmite particles, wherein the boehmite particles have an average dispersed particle size of about 60 nm or less (such as about 10 nm to about 30 nm); and (2) coating the substrate with a second washcoat composition comprising porous micron- sized particles comprising alumina, a platinum salt, and boehmite particles, or comprising porous micron-sized particles comprising alumina impregnated with platinum, and boehmite particles.
  • the boehmite particles in the first washcoat composition make up about 2 wt% to about 15 wt% of the solids in the first washcoat composition. In some embodiments, the boehmite particles in the second washcoat composition make up about 1 wt% to about 8 wt% of the solids in the second washcoat composition. In some embodiments, the first washcoat composition is coated onto the substrate at a thickness of about 100 g/1 to about 300 g/1 of solids. In some embodiments, the second washcoat composition is coated onto the substrate at a thickness of about 40 g/1 to about 150 g/1 of solids.
  • the micron-sized particles comprising ceria make up about 60 wt% to about 95 wt% of the solids in the first washcoat composition. In some embodiments, the micron-sized particles comprising alumina make up about 85 wt% to about 99 wt% of the solids in the second washcoat composition. In some embodiments, the porous micron-sized particles comprising ceria in the first washcoat layer make up about 60 wt% to about 95 wt% of the solids in the first washcoat layer. In some embodiments, the substrate is about 0.5 cm to about 6 cm thick. In some embodiments, the substrate has a transverse profile of about 100 cm 2 to about 600 cm 2 .
  • a method of making a catalyst comprises (1) coating a substrate with a first washcoat composition comprising porous micron-sized particles comprising ceria, a palladium salt, and boehmite particles, wherein the boehmite particles have an average dispersed particle size of about 60 nm or less (such as about 10 nm to about 30 nm); and (2) coating the substrate with a second washcoat composition comprising porous micron-sized particles comprising alumina, a platinum salt, and boehmite particles.
  • the boehmite particles in the first washcoat composition make up about 2 wt% to about 15 wt% of the solids in the first washcoat composition.
  • the boehmite particles in the second washcoat composition make up about 1 wt% to about 8 wt% of the solids in the second washcoat composition.
  • the first washcoat composition is coated onto the substrate at a thickness of about 100 g/1 to about 300 g/1 of solids.
  • the second washcoat composition is coated onto the substrate at a thickness of about 40 g/1 to about 150 g/1 of solids.
  • the micron-sized particles comprising ceria make up about 60 wt% to about 95 wt% of the solids in the first washcoat composition.
  • the micron-sized particles comprising alumina make up about 85 wt% to about 99 wt% of the solids in the second washcoat composition.
  • the porous micron-sized particles comprising ceria in the first washcoat layer make up about 60 wt% to about 95 wt% of the solids in the first washcoat layer.
  • the substrate is about 0.5 cm to about 6 cm thick. In some embodiments, the substrate has a transverse profile of about 100 cm 2 to about 600 cm 2 .
  • a method of making a catalyst comprises (1) coating a substrate with a first washcoat composition comprising porous micron-sized particles comprising ceria impregnated with palladium, and boehmite particles, wherein the boehmite particles have an average dispersed particle size of about 60 nm or less (such as about 10 nm to about 30 nm); and (2) coating the substrate with a second washcoat composition comprising porous micron-sized particles comprising alumina impregnated with platinum, and boehmite particles.
  • the boehmite particles in the first washcoat composition make up about 2 wt% to about 15 wt% of the solids in the first washcoat composition.
  • the boehmite particles in the second washcoat composition make up about 1 wt% to about 8 wt% of the solids in the second washcoat composition.
  • the first washcoat composition is coated onto the substrate at a thickness of about 100 g/1 to about 300 g/1 of solids.
  • the second washcoat composition is coated onto the substrate at a thickness of about 40 g/1 to about 150 g/1 of solids.
  • the micron-sized particles comprising ceria make up about 60 wt% to about 95 wt% of the solids in the first washcoat composition.
  • the micron-sized particles comprising alumina make up about 85 wt% to about 99 wt% of the solids in the second washcoat composition.
  • the porous micron-sized particles comprising ceria in the first washcoat layer make up about 60 wt% to about 95 wt% of the solids in the first washcoat layer.
  • the substrate is about 0.5 cm to about 6 cm thick. In some embodiments, the substrate has a transverse profile of about 100 cm 2 to about 600 cm 2 .
  • a method of making a catalyst comprises (1) coating a substrate with a first washcoat composition comprising porous micron-sized particles comprising ceria, a palladium salt, and boehmite particles, or comprising porous micron-sized particles comprising ceria impregnated with palladium, and boehmite particles, wherein the boehmite particles in the first washcoat composition have an average dispersed particle size of about 60 nm or less (such as about 10 nm to about 30 nm); and (2) coating the substrate with a second washcoat composition comprising porous micron-sized particles comprising alumina, a platinum salt, and boehmite particles, or comprising porous micron-sized particles comprising alumina impregnated with platinum, and boehmite, wherein the boehmite particles in the second washcoat composition have an average dispersed particle size of about 150 nm or more.
  • the boehmite particles in the first washcoat composition make up about 2 wt% to about 15 wt% of the solids in the first washcoat composition. In some embodiments, the boehmite particles in the second washcoat composition make up about 1 wt% to about 8 wt% of the solids in the second washcoat composition. In some embodiments, the first washcoat composition is coated onto the substrate at a thickness of about 100 g/1 to about 300 g/1 of solids. In some embodiments, the second washcoat composition is coated onto the substrate at a thickness of about 40 g/1 to about 150 g/1 of solids.
  • the micron-sized particles comprising ceria make up about 60 wt% to about 95 wt% of the solids in the first washcoat composition. In some embodiments, the micron-sized particles comprising alumina make up about 85 wt% to about 99 wt% of the solids in the second washcoat composition. In some embodiments, the porous micron-sized particles comprising ceria in the first washcoat layer make up about 60 wt% to about 95 wt% of the solids in the first washcoat layer. In some embodiments, the substrate is about 0.5 cm to about 6 cm thick. In some embodiments, the substrate has a transverse profile of about 100 cm 2 to about 600 cm 2 .
  • a method of making a catalyst comprises (1) coating a substrate with a first washcoat composition comprising porous micron-sized particles comprising ceria, a palladium salt, and boehmite particles, wherein the boehmite particles in the first washcoat composition have an average dispersed particle size of about 60 nm or less (such as about 10 nm to about 30 nm); and (2) coating the substrate with a second washcoat composition comprising porous micron-sized particles comprising alumina, a platinum salt, and boehmite particles, wherein the boehmite particles in the second washcoat composition have an average dispersed particle size of about 150 nm or more.
  • the boehmite particles in the first washcoat composition make up about 2 wt% to about 15 wt% of the solids in the first washcoat composition. In some embodiments, the boehmite particles in the second washcoat composition make up about 1 wt% to about 8 wt% of the solids in the second washcoat composition. In some embodiments, the first washcoat composition is coated onto the substrate at a thickness of about 100 g/1 to about 300 g/1 of solids. In some embodiments, the second washcoat composition is coated onto the substrate at a thickness of about 40 g/1 to about 150 g/1 of solids.
  • the micron-sized particles comprising ceria make up about 60 wt% to about 95 wt% of the solids in the first washcoat composition. In some embodiments, the micron-sized particles comprising alumina make up about 85 wt% to about 99 wt% of the solids in the second washcoat composition. In some embodiments, the porous micron-sized particles comprising ceria in the first washcoat layer make up about 60 wt% to about 95 wt% of the solids in the first washcoat layer. In some embodiments, the substrate is about 0.5 cm to about 6 cm thick. In some embodiments, the substrate has a transverse profile of about 100 cm 2 to about 600 cm 2 .
  • a method of making a catalyst comprises (1) coating a substrate with a first washcoat composition comprising porous micron-sized particles comprising ceria impregnated with palladium, and boehmite particles, wherein the boehmite particles in the first washcoat composition have an average dispersed particle size of about 60 nm or less (such as about 10 nm to about 30 nm); and (2) coating the substrate with a second washcoat composition comprising porous micron-sized particles comprising alumina impregnated with platinum, and boehmite, wherein the boehmite particles in the second washcoat composition have an average dispersed particle size of about 150 nm or more.
  • the boehmite particles in the first washcoat composition make up about 2 wt% to about 15 wt% of the solids in the first washcoat composition. In some embodiments, the boehmite particles in the second washcoat composition make up about 1 wt% to about 8 wt% of the solids in the second washcoat composition. In some embodiments, the first washcoat composition is coated onto the substrate at a thickness of about 100 g/1 to about 300 g/1 of solids. In some embodiments, the second washcoat composition is coated onto the substrate at a thickness of about 40 g/1 to about 150 g/1 of solids.
  • the micron-sized particles comprising ceria make up about 60 wt% to about 95 wt% of the solids in the first washcoat composition. In some embodiments, the micron-sized particles comprising alumina make up about 85 wt% to about 99 wt% of the solids in the second washcoat composition. In some embodiments, the porous micron-sized particles comprising ceria in the first washcoat layer make up about 60 wt% to about 95 wt% of the solids in the first washcoat layer. In some embodiments, the substrate is about 0.5 cm to about 6 cm thick. In some embodiments, the substrate has a transverse profile of about 100 cm 2 to about 600 cm 2.
  • a method of making a catalyst comprises (1) coating a substrate with a first washcoat composition comprising porous micron-sized particles comprising ceria, a palladium salt, porous micron-sized particles comprising alumina, and boehmite particles, or comprising porous micron-sized particles comprising ceria impregnated with palladium, porous micron-sized particles comprising alumina, and boehmite particles, wherein the boehmite particles have an average dispersed particle size of about 60 nm or less (such as about 10 nm to about 30 nm); and (2) coating the substrate with a second washcoat composition comprising porous micron-sized particles comprising alumina, a platinum salt, and boehmite particles, or comprising porous micron-sized particles comprising alumina impregnated with platinum, and boehmite particles.
  • the micron-sized particles comprising alumina make up about 2 wt% to about 10 wt% of the solids in the first washcoat composition. In some embodiments, the boehmite particles in the first washcoat composition make up about 2 wt% to about 15 wt% of the solids in the first washcoat composition. In some embodiments, the boehmite particles in the second washcoat composition make up about 1 wt% to about 8 wt% of the solids in the second washcoat composition. In some embodiments, the first washcoat composition is coated onto the substrate at a thickness of about 100 g/1 to about 300 g/1 of solids.
  • the second washcoat composition is coated onto the substrate at a thickness of about 40 g/1 to about 150 g/1 of solids.
  • the micron-sized particles comprising ceria make up about 60 wt% to about 95 wt% of the solids in the first washcoat composition.
  • the micron-sized particles comprising alumina make up about 85 wt% to about 99 wt% of the solids in the second washcoat composition.
  • the porous micron-sized particles comprising ceria in the first washcoat layer make up about 60 wt% to about 95 wt% of the solids in the first washcoat layer.
  • the substrate is about 0.5 cm to about 6 cm thick. In some embodiments, the substrate has a transverse profile of about 100 cm 2 to about 600 cm 2 .
  • a method of making a catalyst comprises (1) coating a substrate with a first washcoat composition comprising porous micron-sized particles comprising ceria, a palladium salt, porous micron-sized particles comprising alumina, and boehmite particles, wherein the boehmite particles have an average dispersed particle size of about 60 nm or less (such as about 10 nm to about 30 nm); and (2) coating the substrate with a second washcoat composition comprising porous micron-sized particles comprising alumina, a platinum salt, and boehmite particles.
  • the micron-sized particles comprising alumina make up about 2 wt% to about 10 wt% of the solids in the first washcoat composition. In some embodiments, the boehmite particles in the first washcoat composition make up about 2 wt% to about 15 wt% of the solids in the first washcoat composition. In some embodiments, the boehmite particles in the second washcoat composition make up about 1 wt% to about 8 wt% of the solids in the second washcoat composition. In some embodiments, the first washcoat composition is coated onto the substrate at a thickness of about 100 g/1 to about 300 g/1 of solids.
  • the second washcoat composition is coated onto the substrate at a thickness of about 40 g/1 to about 150 g/1 of solids.
  • the micron-sized particles comprising ceria make up about 60 wt% to about 95 wt% of the solids in the first washcoat composition.
  • the micron-sized particles comprising alumina make up about 85 wt% to about 99 wt% of the solids in the second washcoat composition.
  • the porous micron-sized particles comprising ceria in the first washcoat layer make up about 60 wt% to about 95 wt% of the solids in the first washcoat layer.
  • the substrate is about 0.5 cm to about 6 cm thick. In some embodiments, the substrate has a transverse profile of about 100 cm 2 to about 600 cm 2 .
  • a method of making a catalyst comprises (1) coating a substrate with a first washcoat composition comprising porous micron-sized particles comprising ceria impregnated with palladium, porous micron-sized particles comprising alumina, and boehmite particles, wherein the boehmite particles have an average dispersed particle size of about 60 nm or less (such as about 10 nm to about 30 nm); and (2) coating the substrate with a second washcoat composition comprising porous micron-sized particles comprising alumina impregnated with platinum, and boehmite particles.
  • the micron-sized particles comprising alumina make up about 2 wt% to about 10 wt% of the solids in the first washcoat composition. In some embodiments, the boehmite particles in the first washcoat composition make up about 2 wt% to about 15 wt% of the solids in the first washcoat composition. In some embodiments, the boehmite particles in the second washcoat composition make up about 1 wt% to about 8 wt% of the solids in the second washcoat composition. In some embodiments, the first washcoat composition is coated onto the substrate at a thickness of about 100 g/1 to about 300 g/1 of solids.
  • the second washcoat composition is coated onto the substrate at a thickness of about 40 g/1 to about 150 g/1 of solids.
  • the micron-sized particles comprising ceria make up about 60 wt% to about 95 wt% of the solids in the first washcoat composition.
  • the micron-sized particles comprising alumina make up about 85 wt% to about 99 wt% of the solids in the second washcoat composition.
  • the porous micron-sized particles comprising ceria in the first washcoat layer make up about 60 wt% to about 95 wt% of the solids in the first washcoat layer.
  • the substrate is about 0.5 cm to about 6 cm thick. In some embodiments, the substrate has a transverse profile of about 100 cm 2 to about 600 cm 2 .
  • a method of making a catalyst comprises (1) coating a substrate with a first washcoat composition comprising porous micron-sized particles comprising ceria, a palladium salt, and boehmite particles, or comprising porous micron-sized particles comprising ceria impregnated with palladium, and boehmite particles, wherein the first washcoat composition is coated onto the substrate to obtain a palladium loading of about 0.1 g/1 to about 0.5 g/1; and (2) coating the substrate with a second washcoat composition comprising porous micron-sized particles comprising alumina, a platinum salt, and boehmite particles, or comprising porous micron-sized particles comprising alumina impregnated with platinum, and boehmite, wherein the second washcoat composition is coated onto the substrate to obtain a platinum loading of about 0.2 g/1 to about 0.7 g/1.
  • the boehmite particles in the first washcoat composition make up about 2 wt% to about 15 wt% of the solids in the first washcoat composition. In some embodiments, the boehmite particles in the second washcoat composition make up about 1 wt% to about 8 wt% of the solids in the second washcoat composition. In some embodiments, the first washcoat composition is coated onto the substrate at a thickness of about 100 g/1 to about 300 g/1 of solids. In some embodiments, the second washcoat composition is coated onto the substrate at a thickness of about 40 g/1 to about 150 g/1 of solids.
  • the micron-sized particles comprising ceria make up about 60 wt% to about 95 wt% of the solids in the first washcoat composition. In some embodiments, the micron-sized particles comprising alumina make up about 85 wt% to about 99 wt% of the solids in the second washcoat composition. In some embodiments, the porous micron-sized particles comprising ceria in the first washcoat layer make up about 60 wt% to about 95 wt% of the solids in the first washcoat layer. In some embodiments, the substrate is about 0.5 cm to about 6 cm thick. In some embodiments, the substrate has a transverse profile of about 100 cm 2 to about 600 cm 2.
  • a method of making a catalyst comprises (1) coating a substrate with a first washcoat composition comprising porous micron-sized particles comprising ceria, a palladium salt, and boehmite particles, wherein the first washcoat composition is coated onto the substrate to obtain a palladium loading of about 0.1 g/1 to about 0.5 g/1; and (2) coating the substrate with a second washcoat composition comprising porous micron-sized particles comprising alumina, a platinum salt, and boehmite particles, wherein the second washcoat composition is coated onto the substrate to obtain a platinum loading of about 0.2 g/1 to about 0.7 g/1.
  • the boehmite particles in the first washcoat composition make up about 2 wt% to about 15 wt% of the solids in the first washcoat composition. In some embodiments, the boehmite particles in the second washcoat composition make up about 1 wt% to about 8 wt% of the solids in the second washcoat composition. In some embodiments, the first washcoat composition is coated onto the substrate at a thickness of about 100 g/1 to about 300 g/1 of solids. In some embodiments, the second washcoat composition is coated onto the substrate at a thickness of about 40 g/1 to about 150 g/1 of solids.
  • the micron-sized particles comprising ceria make up about 60 wt% to about 95 wt% of the solids in the first washcoat composition. In some embodiments, the micron-sized particles comprising alumina make up about 85 wt% to about 99 wt% of the solids in the second washcoat composition. In some embodiments, the porous micron-sized particles comprising ceria in the first washcoat layer make up about 60 wt% to about 95 wt% of the solids in the first washcoat layer. In some embodiments, the substrate is about 0.5 cm to about 6 cm thick. In some embodiments, the substrate has a transverse profile of about 100 cm 2 to about 600 cm 2 .
  • a method of making a catalyst comprises (1) coating a substrate with a first washcoat composition comprising porous micron-sized particles comprising ceria impregnated with palladium, and boehmite particles, wherein the first washcoat composition is coated onto the substrate to obtain a palladium loading of about 0.1 g/1 to about 0.5 g/1; and (2) coating the substrate with a second washcoat composition comprising porous micron-sized particles comprising alumina impregnated with platinum, and boehmite, wherein the second washcoat composition is coated onto the substrate to obtain a platinum loading of about 0.2 g/1 to about 0.7 g/1.
  • the boehmite particles in the first washcoat composition make up about 2 wt% to about 15 wt% of the solids in the first washcoat composition. In some embodiments, the boehmite particles in the second washcoat composition make up about 1 wt% to about 8 wt% of the solids in the second washcoat composition. In some embodiments, the first washcoat composition is coated onto the substrate at a thickness of about 100 g/1 to about 300 g/1 of solids. In some embodiments, the second washcoat composition is coated onto the substrate at a thickness of about 40 g/1 to about 150 g/1 of solids.
  • the micron-sized particles comprising ceria make up about 60 wt% to about 95 wt% of the solids in the first washcoat composition. In some embodiments, the micron-sized particles comprising alumina make up about 85 wt% to about 99 wt% of the solids in the second washcoat composition. In some embodiments, the porous micron-sized particles comprising ceria in the first washcoat layer make up about 60 wt% to about 95 wt% of the solids in the first washcoat layer. In some embodiments, the substrate is about 0.5 cm to about 6 cm thick. In some embodiments, the substrate has a transverse profile of about 100 cm 2 to about 600 cm 2 .
  • a method of making a catalyst comprises (1) coating a substrate with a first washcoat composition comprising porous micron-sized particles comprising ceria, a palladium salt, and boehmite particles, or comprising porous micron-sized particles comprising ceria impregnated with palladium, and boehmite particles, wherein the boehmite particles have an average dispersed particle size of about 60 nm or less (such as about 10 nm to about 30 nm), and wherein the first washcoat composition is coated onto the substrate to obtain a palladium loading of about 0.1 g/1 to about 0.5 g/1; and (2) coating the substrate with a second washcoat composition comprising porous micron-sized particles comprising alumina, a platinum salt, and boehmite particles, or comprising porous micron-sized particles comprising alumina impregnated with platinum, and boehmite, wherein the second washcoat composition is coated onto the substrate to obtain a platinum loading
  • the boehmite particles in the first washcoat composition make up about 2 wt% to about 15 wt% of the solids in the first washcoat composition. In some embodiments, the boehmite particles in the second washcoat composition make up about 1 wt% to about 8 wt% of the solids in the second washcoat composition. In some embodiments, the first washcoat composition is coated onto the substrate at a thickness of about 100 g/1 to about 300 g/1 of solids. In some
  • the second washcoat composition is coated onto the substrate at a thickness of about 40 g/1 to about 150 g/1 of solids.
  • the micron-sized particles comprising ceria make up about 60 wt% to about 95 wt% of the solids in the first washcoat composition.
  • the micron-sized particles comprising alumina make up about 85 wt% to about 99 wt% of the solids in the second washcoat composition.
  • the porous micron-sized particles comprising ceria in the first washcoat layer make up about 60 wt% to about 95 wt% of the solids in the first washcoat layer.
  • the substrate is about 0.5 cm to about 6 cm thick. In some embodiments, the substrate has a transverse profile of about 100 cm 2 to about 600 cm 2 .
  • a method of making a catalyst comprises (1) coating a substrate with a first washcoat composition comprising porous micron-sized particles comprising ceria, a palladium salt, and boehmite particles, wherein the boehmite particles have an average dispersed particle size of about 60 nm or less (such as about 10 nm to about 30 nm), and wherein the first washcoat composition is coated onto the substrate to obtain a palladium loading of about 0.1 g/1 to about 0.5 g/1; and (2) coating the substrate with a second washcoat composition comprising porous micron-sized particles comprising alumina, a platinum salt, and boehmite particles, wherein the second washcoat composition is coated onto the substrate to obtain a platinum loading of about 0.2 g/1 to about 0.7 g/1.
  • the boehmite particles in the first washcoat composition make up about 2 wt% to about 15 wt% of the solids in the first washcoat composition. In some embodiments, the boehmite particles in the second washcoat composition make up about 1 wt% to about 8 wt% of the solids in the second washcoat composition. In some embodiments, the first washcoat composition is coated onto the substrate at a thickness of about 100 g/1 to about 300 g/1 of solids. In some embodiments, the second washcoat composition is coated onto the substrate at a thickness of about 40 g/1 to about 150 g/1 of solids.
  • the micron-sized particles comprising ceria make up about 60 wt% to about 95 wt% of the solids in the first washcoat composition. In some embodiments, the micron-sized particles comprising alumina make up about 85 wt% to about 99 wt% of the solids in the second washcoat composition. In some embodiments, the porous micron-sized particles comprising ceria in the first washcoat layer make up about 60 wt% to about 95 wt% of the solids in the first washcoat layer. In some embodiments, the substrate is about 0.5 cm to about 6 cm thick. In some embodiments, the substrate has a transverse profile of about 100 cm 2 to about 600 cm 2 .
  • a method of making a catalyst comprises (1) coating a substrate with a first washcoat composition comprising porous micron-sized particles comprising ceria impregnated with palladium, and boehmite particles, wherein the boehmite particles have an average dispersed particle size of about 60 nm or less (such as about 10 nm to about 30 nm), and wherein the first washcoat composition is coated onto the substrate to obtain a palladium loading of about 0.1 g/1 to about 0.5 g/1; and (2) coating the substrate with a second washcoat composition comprising porous micron-sized particles comprising alumina impregnated with platinum, andboehmite, wherein the second washcoat composition is coated onto the substrate to obtain a platinum loading of about 0.2 g/1 to about 0.7 g/1.
  • the boehmite particles in the first washcoat composition make up about 2 wt% to about 15 wt% of the solids in the first washcoat composition. In some embodiments, the boehmite particles in the second washcoat composition make up about 1 wt% to about 8 wt% of the solids in the second washcoat composition. In some embodiments, the first washcoat composition is coated onto the substrate at a thickness of about 100 g/1 to about 300 g/1 of solids. In some embodiments, the second washcoat composition is coated onto the substrate at a thickness of about 40 g/1 to about 150 g/1 of solids.
  • the micron-sized particles comprising ceria make up about 60 wt% to about 95 wt% of the solids in the first washcoat composition. In some embodiments, the micron-sized particles comprising alumina make up about 85 wt% to about 99 wt% of the solids in the second washcoat composition. In some embodiments, the porous micron-sized particles comprising ceria in the first washcoat layer make up about 60 wt% to about 95 wt% of the solids in the first washcoat layer. In some embodiments, the substrate is about 0.5 cm to about 6 cm thick. In some embodiments, the substrate has a transverse profile of about 100 cm 2 to about 600 cm 2.
  • a method of making a catalyst comprises (1) coating a substrate with a first washcoat composition comprising porous micron-sized particles comprising ceria, a palladium salt, and boehmite particles, or comprising porous micron-sized particles comprising ceria impregnated with palladium, and boehmite particles, wherein the boehmite particles in the first washcoat composition have an average dispersed particle size of about 60 nm or less (such as about 10 nm to about 30 nm), and wherein the first washcoat composition is coated onto the substrate to obtain a palladium loading of about 0.1 g/1 to about 0.5 g/1; and (2) coating the substrate with a second washcoat composition comprising porous micron-sized particles comprising alumina, a platinum salt, and boehmite particles, or comprising porous micron-sized particles comprising alumina impregnated with platinum, and boehmite particles, wherein the boehmite particles in the
  • the boehmite particles in the first washcoat composition make up about 2 wt% to about 15 wt% of the solids in the first washcoat composition. In some embodiments, the boehmite particles in the second washcoat composition make up about 1 wt% to about 8 wt% of the solids in the second washcoat composition. In some embodiments, the first washcoat composition is coated onto the substrate at a thickness of about 100 g/1 to about 300 g/1 of solids. In some embodiments, the second washcoat composition is coated onto the substrate at a thickness of about 40 g/1 to about 150 g/1 of solids.
  • the micron-sized particles comprising ceria make up about 60 wt% to about 95 wt% of the solids in the first washcoat composition. In some embodiments, the micron-sized particles comprising alumina make up about 85 wt% to about 99 wt% of the solids in the second washcoat composition. In some embodiments, the porous micron-sized particles comprising ceria in the first washcoat layer make up about 60 wt% to about 95 wt% of the solids in the first washcoat layer. In some embodiments, the substrate is about 0.5 cm to about 6 cm thick. In some embodiments, the substrate has a transverse profile of about 100 cm 2 to about 600 cm 2 .
  • a method of making a catalyst comprises (1) coating a substrate with a first washcoat composition comprising porous micron-sized particles comprising ceria, a palladium salt, and boehmite particles, wherein the boehmite particles in the first washcoat composition have an average dispersed particle size of about 60 nm or less (such as about 10 nm to about 30 nm), and wherein the first washcoat composition is coated onto the substrate to obtain a palladium loading of about 0.1 g/1 to about 0.5 g/1; and (2) coating the substrate with a second washcoat composition comprising porous micron-sized particles comprising alumina, a platinum salt, and boehmite particles, wherein the boehmite particles in the second washcoat composition have an average dispersed particle size of about 150 nm or more, and wherein the second washcoat composition is coated onto the substrate to obtain a platinum loading of about 0.2 g/1 to about 0.7 g/1.
  • the boehmite particles in the first washcoat composition make up about 2 wt% to about 15 wt% of the solids in the first washcoat composition. In some embodiments, the boehmite particles in the second washcoat composition make up about 1 wt% to about 8 wt% of the solids in the second washcoat composition. In some embodiments, the first washcoat composition is coated onto the substrate at a thickness of about 100 g/1 to about 300 g/1 of solids. In some embodiments, the second washcoat composition is coated onto the substrate at a thickness of about 40 g/1 to about 150 g/1 of solids.
  • the micron-sized particles comprising ceria make up about 60 wt% to about 95 wt% of the solids in the first washcoat composition. In some embodiments, the micron-sized particles comprising alumina make up about 85 wt% to about 99 wt% of the solids in the second washcoat composition. In some embodiments, the porous micron-sized particles comprising ceria in the first washcoat layer make up about 60 wt% to about 95 wt% of the solids in the first washcoat layer. In some embodiments, the substrate is about 0.5 cm to about 6 cm thick. In some embodiments, the substrate has a transverse profile of about 100 cm 2 to about 600 cm 2 .
  • a method of making a catalyst comprises (1) coating a substrate with a first washcoat composition comprising porous micron-sized particles comprising ceria impregnated with palladium, and boehmite particles, wherein the boehmite particles in the first washcoat composition have an average dispersed particle size of about 60 nm or less (such as about 10 nm to about 30 nm), and wherein the first washcoat composition is coated onto the substrate to obtain a palladium loading of about 0.1 g/1 to about 0.5 g/1; and (2) coating the substrate with a second washcoat composition comprising porous micron-sized particles comprising alumina impregnated with platinum, and boehmite particles, wherein the boehmite particles in the second washcoat composition have an average dispersed particle size of about 150 nm or more, and wherein the second washcoat composition is coated onto the substrate to obtain a platinum loading of about 0.2 g/1 to about 0.7 g/1.
  • the boehmite particles in the first washcoat composition make up about 2 wt% to about 15 wt% of the solids in the first washcoat composition. In some embodiments, the boehmite particles in the second washcoat composition make up about 1 wt% to about 8 wt% of the solids in the second washcoat composition. In some embodiments, the first washcoat composition is coated onto the substrate at a thickness of about 100 g/1 to about 300 g/1 of solids. In some embodiments, the second washcoat composition is coated onto the substrate at a thickness of about 40 g/1 to about 150 g/1 of solids.
  • the micron-sized particles comprising ceria make up about 60 wt% to about 95 wt% of the solids in the first washcoat composition. In some embodiments, the micron-sized particles comprising alumina make up about 85 wt% to about 99 wt% of the solids in the second washcoat composition. In some embodiments, the porous micron-sized particles comprising ceria in the first washcoat layer make up about 60 wt% to about 95 wt% of the solids in the first washcoat layer. In some embodiments, the substrate is about 0.5 cm to about 6 cm thick. In some embodiments, the substrate has a transverse profile of about 100 cm 2 to about 600 cm 2.
  • a method of making a catalyst comprises (1) coating a substrate with a first washcoat composition comprising porous micron-sized particles comprising ceria, a palladium salt, porous micron-sized particles comprising alumina, and boehmite particles, or comprising porous micron-sized particles comprising ceria impregnated with palladium, porous micron-sized particles comprising alumina, and boehmite particles, wherein the boehmite particles have an average dispersed particle size of about 60 nm or less (such as about 10 nm to about 30 nm), and wherein the first washcoat composition is coated onto the substrate to obtain a palladium loading of about 0.1 g/1 to about 0.5 g/1; and (2) coating the substrate with a second washcoat composition comprising porous micron-sized particles comprising alumina, a platinum salt, and boehmite particles, or comprising porous micron-sized particles comprising alumina impregnated with platinum
  • the micron-sized particles comprising alumina make up about 2 wt% to about 10 wt% of the solids in the first washcoat composition.
  • the second washcoat composition is coated onto the substrate to obtain a platinum loading of about 0.2 g/1 to about 0.7 g/1.
  • the boehmite particles in the first washcoat composition make up about 2 wt% to about 15 wt% of the solids in the first washcoat composition.
  • the boehmite particles in the second washcoat composition make up about 1 wt% to about 8 wt% of the solids in the second washcoat composition.
  • the first washcoat composition is coated onto the substrate at a thickness of about 100 g/1 to about 300 g/1 of solids. In some
  • the second washcoat composition is coated onto the substrate at a thickness of about 40 g/1 to about 150 g/1 of solids.
  • the micron-sized particles comprising ceria make up about 60 wt% to about 95 wt% of the solids in the first washcoat composition.
  • the micron-sized particles comprising alumina make up about 85 wt% to about 99 wt% of the solids in the second washcoat composition.
  • the porous micron-sized particles comprising ceria in the first washcoat layer make up about 60 wt% to about 95 wt% of the solids in the first washcoat layer.
  • the substrate is about 0.5 cm to about 6 cm thick. In some embodiments, the substrate has a transverse profile of about 100 cm 2 to about 600 cm 2 .
  • a method of making a catalyst comprises (1) coating a substrate with a first washcoat composition comprising porous micron-sized particles comprising ceria, a palladium salt, porous micron-sized particles comprising alumina, and boehmite particles, wherein the boehmite particles have an average dispersed particle size of about 60 nm or less (such as about 10 nm to about 30 nm), and wherein the first washcoat composition is coated onto the substrate to obtain a palladium loading of about 0.1 g/1 to about 0.5 g/1; and (2) coating the substrate with a second washcoat composition comprising porous micron-sized particles comprising alumina, a platinum salt, and boehmite particles.
  • the micron- sized particles comprising alumina make up about 2 wt% to about 10 wt% of the solids in the first washcoat composition, and wherein the second washcoat composition is coated onto the substrate to obtain a platinum loading of about 0.2 g/1 to about 0.7 g/1.
  • the boehmite particles in the first washcoat composition make up about 2 wt% to about 15 wt% of the solids in the first washcoat composition.
  • the boehmite particles in the second washcoat composition make up about 1 wt% to about 8 wt% of the solids in the second washcoat composition.
  • the first washcoat composition is coated onto the substrate at a thickness of about 100 g/1 to about 300 g/1 of solids. In some
  • the second washcoat composition is coated onto the substrate at a thickness of about 40 g/1 to about 150 g/1 of solids.
  • the micron-sized particles comprising ceria make up about 60 wt% to about 95 wt% of the solids in the first washcoat composition.
  • the micron-sized particles comprising alumina make up about 85 wt% to about 99 wt% of the solids in the second washcoat composition.
  • the porous micron-sized particles comprising ceria in the first washcoat layer make up about 60 wt% to about 95 wt% of the solids in the first washcoat layer.
  • the substrate is about 0.5 cm to about 6 cm thick. In some embodiments, the substrate has a transverse profile of about 100 cm 2 to about 600 cm 2 .
  • a method of making a catalyst comprises (1) coating a substrate with a first washcoat composition comprising porous micron-sized particles comprising ceria impregnated with palladium, porous micron-sized particles comprising alumina, and boehmite particles, wherein the boehmite particles have an average dispersed particle size of about 60 nm or less (such as about 10 nm to about 30 nm), and wherein the first washcoat composition is coated onto the substrate to obtain a palladium loading of about 0.1 g/1 to about 0.5 g/1; and (2) coating the substrate with a second washcoat composition comprising porous micron-sized particles comprising alumina impregnated with platinum, and boehmite particles.
  • the micron-sized particles comprising alumina make up about 2 wt% to about 10 wt% of the solids in the first washcoat composition, and wherein the second washcoat composition is coated onto the substrate to obtain a platinum loading of about 0.2 g/1 to about 0.7 g/1.
  • the boehmite particles in the first washcoat composition make up about 2 wt% to about 15 wt% of the solids in the first washcoat composition.
  • the boehmite particles in the second washcoat composition make up about 1 wt% to about 8 wt% of the solids in the second washcoat composition.
  • the first washcoat composition is coated onto the substrate at a thickness of about 100 g/1 to about 300 g/1 of solids.
  • the second washcoat composition is coated onto the substrate at a thickness of about 40 g/1 to about 150 g/1 of solids.
  • the micron-sized particles comprising ceria make up about 60 wt% to about 95 wt% of the solids in the first washcoat composition.
  • the micron-sized particles comprising alumina make up about 85 wt% to about 99 wt% of the solids in the second washcoat composition.
  • the porous micron-sized particles comprising ceria in the first washcoat layer make up about 60 wt% to about 95 wt% of the solids in the first washcoat layer.
  • the substrate is about 0.5 cm to about 6 cm thick. In some embodiments, the substrate has a transverse profile of about 100 cm 2 to about 600 cm 2 .
  • a method of making a catalyst comprises (1) coating a substrate with a first washcoat composition comprising about 85 wt% to about 90 wt% (such as about 88 wt%) porous micron-sized particles comprising ceria, a palladium salt, about 3 wt% to about 6 wt% (such as about 4.6 wt%) porous micron-sized particles comprising alumina, and about 5 wt% to about 10 wt% (such as about 7 wt%) boehmite particles, or comprising about 85 wt% to about 90 wt% (such as about 88 wt%) porous micron-sized particles comprising ceria impregnated with palladium, about 3 wt% to about 6 wt% (such as about 4.6 wt%) porous micron-sized particles comprising alumina, and about 5 wt% to about 10 wt% (such as about 7 wt%) boehmite particles, where
  • the second washcoat composition is coated onto the substrate to obtain a platinum loading of about 0.2 g/1 to about 0.7 g/1.
  • the first washcoat composition is coated onto the substrate at a thickness of about 100 g/1 to about 300 g/1 of solids.
  • the second washcoat composition is coated onto the substrate at a thickness of about 40 g/1 to about 150 g/1 of solids.
  • the porous micron-sized particles comprising ceria in the first washcoat layer make up about 60 wt% to about 95 wt% of the solids in the first washcoat layer.
  • the substrate is about 0.5 cm to about 6 cm thick.
  • the substrate has a transverse profile of about 100 cm 2 to about 600 cm 2 .
  • a method of making a catalyst comprises (1) coating a substrate with a first washcoat composition comprising about 85 wt% to about 90 wt% (such as about 88 wt%) porous micron-sized particles comprising ceria, a palladium salt, about 3 wt% to about 6 wt% (such as about 4.6 wt%) porous micron-sized particles comprising alumina, and about 5 wt% to about 10 wt% (such as about 7 wt%) boehmite particles, wherein the boehmite particles have an average dispersed particle size of about 60 nm or less (such as about 10 nm to about 30 nm), and wherein the first washcoat composition is coated onto the substrate to obtain a palladium loading of about 0.1 g/1 to about 0.5 g/1; and (2) coating the substrate with a second washcoat composition comprising about 85 wt% to about 99 wt% (such as about 95 wt%) porous
  • the second washcoat composition is coated onto the substrate to obtain a platinum loading of about 0.2 g/1 to about 0.7 g/1.
  • the first washcoat composition is coated onto the substrate at a thickness of about 100 g/1 to about 300 g/1 of solids.
  • the second washcoat composition is coated onto the substrate at a thickness of about 40 g/1 to about 150 g/1 of solids.
  • the porous micron-sized particles comprising ceria in the first washcoat layer make up about 60 wt% to about 95 wt% of the solids in the first washcoat layer.
  • the substrate is about 0.5 cm to about 6 cm thick.
  • the substrate has a transverse profile of about 100 cm 2 to about 600 cm 2 .
  • a method of making a catalyst comprises (1) coating a substrate with a first washcoat composition comprising about 85 wt% to about 90 wt% (such as about 88 wt%) porous micron-sized particles comprising ceria impregnated with palladium, about 3 wt% to about 6 wt% (such as about 4.6 wt%) porous micron-sized particles comprising alumina, and about 5 wt% to about 10 wt% (such as about 7 wt%) boehmite particles, wherein the boehmite particles have an average dispersed particle size of about 60 nm or less (such as about 10 nm to about 30 nm), and wherein the first washcoat composition is coated onto the substrate to obtain a palladium loading of about 0.1 g/1 to about 0.5 g/1; and (2) coating the substrate with a second washcoat composition comprising about 85 wt% to about 99 wt% (such as about 95 wt%) por
  • the second washcoat composition is coated onto the substrate to obtain a platinum loading of about 0.2 g/1 to about 0.7 g/1.
  • the first washcoat composition is coated onto the substrate at a thickness of about 100 g/1 to about 300 g/1 of solids.
  • the second washcoat composition is coated onto the substrate at a thickness of about 40 g/1 to about 150 g/1 of solids.
  • the porous micron-sized particles comprising ceria in the first washcoat layer make up about 60 wt% to about 95 wt% of the solids in the first washcoat layer.
  • the substrate is about 0.5 cm to about 6 cm thick.
  • the substrate has a transverse profile of about 100 cm 2 to about 600 cm 2 .
  • the catalysts described herein can be part of an exhaust treatment system, which can be used to treat exhaust gasses.
  • An exhaust treatment system comprises the catalyst and a conduit for exhaust gas.
  • the conduit fluidly connects the catalyst to an exhaust gas source, such as a stove, a furnace, a fireplace or a generator.
  • the exhaust gas source is indoors.
  • the exhaust gas source burns a fuel (such as natural gas, a combustible hydrocarbon liquid, oil, kerosene, coal, or wood), thereby forming an exhaust gas.
  • the exhaust gas can comprise carbon monoxide or hydrocarbons (such as methane or non-methane hydrocarbons).
  • the exhaust gas can be treated by contacting the exhaust gas with the catalyst.
  • the catalyst can oxidize the carbon monoxide or certain other exhaust gas components.
  • the catalysts described herein can oxidize carbon monoxide in exhaust gas with better performance than a single layer catalyst comprising micron-sized particles comprising alumina impregnated with platinum by wet-chemistry methods.
  • the catalyst can oxidize a greater portion of the carbon monoxide in exhaust gas at temperatures lower than about 100 °C than a single layer catalyst comprising micron-sized particles comprising alumina impregnated with platinum by wet-chemistry methods.
  • the catalyst can oxidize substantially all of the carbon monoxide in an exhaust gas at a temperature above about 130 °C with a lower platinum loading or platinum group metal loading than a single layer catalyst comprising micron-sized particles comprising alumina impregnated with platinum by wet-chemistry methods.
  • the catalyst oxidizes substantially all of the carbon monoxide in an exhaust gas at a temperature above about 130 °C with a platinum group metal loading of about 0.85 g/1 or less (such as about 0.8 g/1 or less, about 0.75 g/1 or less, or about 0.7 g/1 or less). In some embodiments, the catalyst oxidizes substantially all of the carbon monoxide in an exhaust gas at a temperature above about 130 °C with a platinum group metal loading of about 0.6 g/1 to about 0.85 g/1 (such as about 0.6 g/1 to about 0.8 g/1, about 0.65 g/1 to about 0.75 g/1, about 0.65 g/1 to about 0.7 g/1, or about 0.67 g/1).
  • the catalyst oxidizes substantially all of the carbon monoxide in an exhaust gas at a temperature above about 130 °C with a platinum loading of about 0.85 g/1 or less (such as about 0.8 g/1 or less, about 0.75 g/1 or less, about 0.7 g/1 or less, about 0.65 g/1 or less, about 0.6 g/1 or less, about 0.55 g/1 or less, or about 0.5 g/1 or less). In some embodiments, the catalyst oxidizes substantially all of the carbon monoxide in an exhaust gas at a temperature above about 130 °C with a platinum loading of about 0.4 g/1 to about 0.85 g/1 (such as about 0.
  • Embodiment 1 A catalyst comprising:
  • the first washcoat layer comprising porous micron-sized particles comprising ceria impregnated with palladium, and alumina derived from boehmite particles;
  • the second washcoat layer comprising porous micron-sized particles comprising alumina impregnated with platinum, and alumina derived from boehmite particles.
  • Embodiment 2 The catalyst of embodiment 1, wherein the micron-sized particles comprising ceria in the first washcoat layer are impregnated with palladium by wet-chemistry methods.
  • Embodiment 3 The catalyst of embodiment 1 or 2, wherein the micron-sized particles comprising alumina in the second washcoat layer are impregnated with platinum by wet- chemistry methods.
  • Embodiment 4 The catalyst of any one of embodiments 1 -3, wherein the boehmite particles used to derive the alumina in the first washcoat layer have an average dispersed particle size of about 60 nm or less.
  • Embodiment 5 The catalyst of any one of embodiments 1 -4, wherein the boehmite particles used to derive the alumina in the first washcoat layer have a BET surface area of about 120 m 2 /g or more.
  • Embodiment 6. The catalyst of any one of embodiments 1 -5, wherein the boehmite particles used to derive the alumina in the second washcoat layer have an average dispersed particle size of about 150 nm or more.
  • Embodiment 7 The catalyst of any one of embodiments 1 -6, wherein the boehmite particles used to derive the alumina in the second washcoat layer have a BET surface area of about 250 m 2 /g or less.
  • Embodiment 8 The catalyst of any one of embodiments 1 -7, wherein the micron-sized particles comprising alumina in the second washcoat layer are stabilized with lanthana.
  • Embodiment 9 The catalyst of any one of embodiments 1 -8, wherein the first washcoat layer further comprises porous micron-sized particles comprising alumina.
  • Embodiment 10 The catalyst of embodiment 9, wherein the porous micron-sized particles comprising alumina in the first washcoat layer are impregnated with palladium.
  • Embodiment 11 The catalyst of embodiment 10, wherein the porous micron-sized particles comprising alumina in the first washcoat layer are impregnated with palladium by wet- chemistry methods.
  • Embodiment 12 The catalyst of embodiment 9, wherein the porous micron-sized particles comprising alumina in the first washcoat layer are substantially free of palladium.
  • Embodiment 13 The catalyst of any one of embodiments 9-12, wherein the micron-sized particles comprising alumina are stabilized with lanthanaA
  • Embodiment 14 The catalyst of any one of embodiments 9-13, wherein the micron-sized particles comprising alumina in the first washcoat layer make up about 2 wt% to about 10 wt% of the solids in the first washcoat layer.
  • Embodiment 15 The catalyst of any one of embodiments 1-14, wherein the alumina derived from boehmite in the first washcoat layer makes up about 2 wt% to about 15 wt% of the solids in the first washcoat layer.
  • Embodiment 16 The catalyst of any one of embodiments 1-15, wherein the alumina derived from boehmite in the second washcoat layer makes up about 1 wt% to about 8 wt% of the solids in the second washcoat layer.
  • Embodiment 17 The catalyst of any one of embodiments 1-16, wherein the first washcoat layer has a thickness of about 100 g/1 to about 300 g/1.
  • Embodiment 18 The catalyst of any one of embodiments 1-17, wherein the second washcoat layer has a thickness of about 40 g/1 to about 150 g/1.
  • Embodiment 19 The catalyst of any one of embodiments 1-18, wherein the first washcoat layer has a palladium loading of about 0.1 g/1 to about 0.5 g/1.
  • Embodiment 20 The catalyst of any one of embodiments 1-19, wherein the second washcoat layer has a platinum loading of about 0.2 g/1 to about 0.7 g/1.
  • Embodiment 21 The catalyst of any one of embodiments 1-20, wherein the catalyst has a platinum group metal loading of about 0.3 g/1 to about 1.2 g/1.
  • Embodiment 22 The catalyst of any one of embodiments 1-21 , wherein the micron-sized particles comprising ceria in the first washcoat layer make up about 60 wt% to about 95 wt% of the solids in the first washcoat layer.
  • Embodiment 23 The catalyst of any one of embodiments 1-22, wherein the micron-sized particles comprising alumina in the second washcoat layer make up about 85 wt% to about 99 wt% of the solids in the second washcoat layer.
  • Embodiment 24 The catalyst of any one of embodiments 1-23, wherein the substrate comprises cordierite.
  • Embodiment 25 The catalyst of any one of embodiments 1-24, wherein the substrate has a honeycomb structure.
  • Embodiment 26 The catalyst of any one of embodiments 1-25, wherein the substrate is about 0.5 cm to about 6 cm thick.
  • Embodiment 27 The catalyst of any one of embodiments 1-26, wherein the substrate has a transverse profile of about 100 cm 2 to about 600 cm 2 .
  • Embodiment 28 An exhaust treatment system comprising a conduit for exhaust gas and the catalyst according to any one of embodiment 1-27.
  • Embodiment 29 The exhaust treatment system of embodiment 28, wherein the catalyst is fiuidly connected to an exhaust gas source.
  • Embodiment 30 The exhaust treatment system of embodiment 29, wherein the exhaust gas source burns natural gas, a combustible hydrocarbon liquid, oil, kerosene, coal, or wood.
  • Embodiment 31 The exhaust treatment system of embodiment 29 or 30, wherein the exhaust gas source is a stove, a furnace, a fireplace, or a generator.
  • Embodiment 32 A method of treating an exhaust gas comprising contacting the exhaust gas with the catalyst according to any one of embodiments 1 -27.
  • Embodiment 33 A method of making a catalyst comprising:
  • a substrate with a first washcoat composition comprising:
  • porous micron-sized particles comprising ceria, a palladium salt, and boehmite particles, or
  • porous micron-sized particles comprising ceria impregnated with palladium, and boehmite particles
  • porous micron-sized particles comprising alumina, a platinum salt, and boehmite particles, or
  • porous micron-sized particles comprising alumina impregnated with platinum, and boehmite particles.
  • Embodiment 34 The method of embodiment 33, wherein the first washcoat composition comprises porous micron-sized particles comprising ceria, a palladium salt, and boehmite particles.
  • Embodiment 35 The method of embodiment 33, wherein the first washcoat composition comprises porous micron-sized particles comprising ceria impregnated with palladium, and boehmite particles.
  • Embodiment 36 The method of any one of embodiments 33-35, wherein the second washcoat composition comprises porous micron-sized particles comprising ceria impregnated with palladium, and boehmite particles.
  • Embodiment 37 The method of any one of embodiments 34-35, wherein the second washcoat composition comprises porous micron-sized particles comprising alumina impregnated with platinum, and boehmite particles.
  • Embodiment 38 The method of any one of embodiments 33-37, further comprising drying the first washcoat composition after it has been coated onto the substrate.
  • Embodiment 39 The method of any one of embodiments 33-38, further comprising calcining the substrate after the first washcoat composition has been coated onto the substrate.
  • Embodiment 40 The method of any one of embodiments 33-39, further comprising drying the second washcoat composition after it has been coated onto the substrate.
  • Embodiment 41 The method of any one of embodiments 33-40, further comprising calcining the substrate after the second washcoat composition has been coated onto the substrate.
  • Embodiment 42 The method of any one of embodiments 33-41 , wherein the substrate is coated with the first washcoat composition prior to being coated with the second washcoat composition.
  • Embodiment 43 The method of any one of embodiments 33-42, wherein the boehmite particles in the first washcoat composition have an average dispersed particle size of about 60 nm or less.
  • Embodiment 44 The method of any one of embodiments 33-43, wherein the boehmite particles in the first washcoat composition have a BET surface area of about 120 m 2 /s or more.
  • Embodiment 45 The method of any one of embodiments 33-44, wherein the boehmite particles in the second washcoat layer has an average dispersed particle size of about 150 nm or more.
  • Embodiment 46 The method of any one of embodiments 33-45, wherein the boehmite particles in the second washcoat layer have a BET surface area of about 250 m 2 /g or less.
  • Embodiment 47 The method of any one of embodiments 33-46, wherein the micron- sized particles comprising alumina in the second washcoat composition are stabilized with lanthana.
  • Embodiment 48 The method of any one of embodiments 33-47, wherein the first washcoat composition further comprises porous micron-sized particles comprising alumina.
  • Embodiment 49 The method of embodiment 48, wherein the micron-sized particles comprising alumina in the first washcoat composition are stabilized with lanthana.
  • Embodiment 50 The method of embodiment 48 or 49, wherein the micron-sized particles comprising alumina in the first washcoat composition make up about 2 wt% to about 10 wt% of the solids in the first washcoat composition.
  • Embodiment 51 The method of any one of embodiments 33-50, wherein the boehmite particles in the first washcoat composition make up about 2 wt% to about 15 wt% of the solids in the first washcoat composition.
  • Embodiment 52 The method of any one of embodiments 33-51 , wherein the boehmite particles in the second washcoat composition make up about 1 wt% to about 8 wt% of the solids in the second washcoat composition.
  • Embodiment 53 The method of any one of embodiments 33-52, wherein the first washcoat composition is coated onto the substrate at a thickness of about 100 g/1 to about 300 g/1 of solids.
  • Embodiment 54 The method of any one of embodiments 33-53, wherein the second washcoat composition is coated onto the substrate at a thickness of about 40 g/1 to about 150 g/1 of solids.
  • Embodiment 55 The method of any one of embodiments 33-54, wherein the first washcoat composition is coated onto the substrate to obtain a palladium loading of about 0.1 g/1 to about 0.5 g/1.
  • Embodiment 56 The method of any one of embodiments 33-55, wherein the second washcoat composition is coated onto the substrate to obtain a platinum loading of about 0.2 g/1 to about 0.7 g/1.
  • Embodiment 57 The method of any one of embodiments 33-56, wherein the micron- sized particles comprising ceria make up about 80 wt% to about 95 wt% of the solids in the first washcoat composition.
  • Embodiment 58 The method of any one of embodiments 33-57, wherein the micron- sized particles comprising alumina make up about 85 wt% to about 99 wt% of the solids in the second washcoat composition.
  • Embodiment 59 The method of any one of embodiments 33-58, wherein the substrate comprises cordierite.
  • Embodiment 60 The method of any one of embodiments 33-59, wherein the substrate has a honeycomb structure.
  • Embodiment 61 The method of any one of embodiments 33-60, wherein the substrate is about 1 cm to about 4 cm thick.
  • Embodiment 62 The catalyst of any one of embodiments 33-61 , wherein the substrate has a transverse profile of about 100 to about 600 cm 2 .
  • Embodiment 63 The catalyst made according to the method of any one of embodiments 33-62.
  • a first catalyst was prepared as follows.
  • a washcoat composition was formed by combining MI-386 particles (porous micron-sized alumina particles stabilized with lanthana), boehmite, and a platinum salt (chloroplatinic acid) in water.
  • the washcoat composition was coated onto a substrate at a thickness of 100 g/1 of solids.
  • the washcoat was dried and the coated substrate calcined.
  • the resulting substrate was coated with a single washcoat layer with a platinum loading of 0.9 g/1.
  • a second catalyst was prepared as follows.
  • a first washcoat composition was formed by combining 88 wt% HSA-20 particles (porous micron-sized ceria particles), palladium (II) nitrate, 4.6 wt% MI-368 particles, and 7 wt% DISPAL® 11N7-80 boehmite particles in water.
  • the first washcoat composition was coated onto a substrate at a thickness of 220 g/1 of solids.
  • the washcoat was dried and the coated substrate calcined.
  • the resulting substrate was coated with a single washcoat layer with a palladium loading of 0.22 g/1.
  • a second washcoat composition was formed by combining 95 wt% MI-386 particles, a platinum salt (chloroplatinic acid), and 5 wt% DISPAL® 1 1N7-80 boehmite particles in water.
  • the washcoat composition was coated onto the substrate (which already includes the first washcoat layer) at a thickness of 65 g/1.
  • the washcoat was dried and the coated substrate calcined.
  • the resulting substrate was coated with two washcoat layers.
  • the first (bottom) washcoat layer provided a palladium loading of 0.22 g/1
  • the second (top) washcoat layer provided a platinum loading of 0.45 g/1.
  • a third catalyst (Catalyst C) was prepared as follows.
  • a first washcoat composition was formed by combining 89 wt% HSA-20 particles (porous micron-sized ceria particles), 11 wt% DISPERAL® P2 boehmite particles, and palladium (II) nitrate in water.
  • the first washcoat composition was coated onto a substrate at a thickness of 241 g/1 of solids.
  • the washcoat was dried and the coated substrate calcined.
  • the resulting substrate was coated with a single washcoat layer with a palladium loading of 0.21 g/1.
  • a second washcoat composition was formed by combining 95 wt% MI-386 particles, 5 wt% DISPAL® 1 1N7-80 boehmite particles, and a platinum salt (chloroplatinic acid) in water.
  • the washcoat composition was coated onto the substrate (which already includes the first washcoat layer) at a thickness of 60 g/1.
  • the washcoat was dried and the coated substrate calcined.
  • the resulting substrate was coated with two washcoat layers.
  • the first (bottom) washcoat layer provided a palladium loading of 0.21 g/1
  • the second (top) washcoat layer provided a platinum loading of 0.46 g/1.
  • a synthetic exhaust gas (500 ppm CO, 2000 ppm CH 4 , 5% C0 2 , 5% 0 2 , 5% H 2 0, and the balance N 2 ) passed through the three catalysts (Catalyst A, Catalyst B, and Catalyst C) at a gas hourly space velocity (GHSV) of 50,000 h "1 with increasing temperature.
  • GHSV gas hourly space velocity
  • the amount of carbon monoxide exiting the catalysts was measured and plotted as against the temperature, as shown in FIG. 2.
  • Catalyst A showed minimal catalysis of carbon monoxide below about 100 °C, with nearly complete catalysis of the carbon monoxide at about 125 °C.
  • Catalyst B catalyzed the carbon monoxide in a near linear relationship with temperature between about 25 °C and about 105 °C, thereafter exhibiting a sharp increase in catalytic efficiency with increased temperature.
  • Catalyst A catalyzed over 10% of the carbon monoxide at about 50 °C, over 20% of the carbon monoxide at about 90 °C, and nearly all of the carbon monoxide at about 125 °C.
  • Catalyst C was more efficient than both Catalyst A and Catalyst B, and catalyzed over 10% of the carbon monoxide at about 30 °C, over 20% of the carbon monoxide at about 50 °C, over 30% of the carbon monoxide at about 90 °C, over 40% of the carbon monoxide at about 100 °C, over 50% of the carbon monoxide at about 105 °C, and substantially all of the carbon monoxide at about 1 15 °C.

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Abstract

La présente invention concerne des catalyseurs pour traiter des gaz d'échappement comme ceux résultant de la combustion de gaz naturel, de liquides hydrocarbonés combustibles, de pétrole, de kérosène, de charbon ou de bois, et d'autres combustibles organiques. Un exemple de catalyseur comprend un substrat, une première couche de revêtement catalytique comprenant des particules de taille micrométrique poreuse comprenant du palladium sur de l'oxyde de cérium, et de l'alumine dérivée de la boehmite, et une seconde couche d'imprégnation comprenant des particules de taille micrométrique poreuse comprenant du platine sur de l'alumine, et de l'alumine dérivée de la boehmite. L'invention concerne également des composants supplémentaires qui peuvent être utilisés dans les couches de revêtement catalytique.
PCT/EP2018/050559 2017-01-10 2018-01-10 Catalyseurs pour traiter des gaz d'échappement WO2018130569A1 (fr)

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5958828A (en) * 1995-02-24 1999-09-28 Mazda Motor Corporation Catalyst for purifying exhaust gas
US20100183490A1 (en) * 2009-01-16 2010-07-22 BASF Catalystic LLC Diesel oxidation catalyst and use thereof in diesel and advanced combustion diesel engine systems
US20150165423A1 (en) * 2013-12-16 2015-06-18 Basf Corporation Manganese-Containing Diesel Oxidation Catalyst
US20150165418A1 (en) * 2013-10-22 2015-06-18 SDCmaterials, Inc. Compositions of lean nox trap (lnt) systems and methods of making and using same

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5958828A (en) * 1995-02-24 1999-09-28 Mazda Motor Corporation Catalyst for purifying exhaust gas
US20100183490A1 (en) * 2009-01-16 2010-07-22 BASF Catalystic LLC Diesel oxidation catalyst and use thereof in diesel and advanced combustion diesel engine systems
US20150165418A1 (en) * 2013-10-22 2015-06-18 SDCmaterials, Inc. Compositions of lean nox trap (lnt) systems and methods of making and using same
US20150165423A1 (en) * 2013-12-16 2015-06-18 Basf Corporation Manganese-Containing Diesel Oxidation Catalyst

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